Sir2000 datetime processing considerations

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Introduction

This page presents date processing issues, including usage of the Sir2000 User Language Tools past the year 1999, an explanation of its processing of dates, and any rules and restrictions you must follow to achieve correct results using date values with the Sir2000 User Language Tools.

Sir2000 User Language Tools dates

The Sir2000 User Language Tools uses dates in the following ways:

  • To examine the CPU clock (as returned by the STCK hardware instruction) to determine the current date, in case the Sir2000 User Language Tools is under a rental or trial agreement.
  • As arguments to various $functions, and as returned values from them.
  • To set a date for testing with the APPDATE command.
  • See SirLib and SirPro for date processing considerations for those products as part of the Sir2000 User Language Tools.

Two views of datetime $functions

This page refers to datetime $functions in two product groups:

In operational terms, there are two classes of datetime $functions:

  • $functions using a numeric value to represent a datetime, where 0 represents 12:00 AM, 1 January 1900; for example, $Sir_Date2NM and $Sir_NM2Date (number of milliseconds since the start of 1900).

    These $functions, and $Sir_Date, have the following error return values:

    • -9.E12 for numeric result $functions
    • null string for string result $functions

    They also perform non-strict matching of date strings to date formats. For example, a leading blank is allowed for the HH token.

    All numeric datetime $functions, and $Sir_Date, are part of the Sirius Functions.

  • Other $functions that only manipulate strings and associated datetime formats ($Sir_Date not included in this class); for example, $Sir_DateChg (add number of days to given date).

    These $functions have error return values of a variable number of asterisks (or, in the case of $Sir_DateDif, the value 99,999,999). They also perform strict matching of date strings to date formats; for example, a leading blank is not allowed for the HH token. These $functions produce the same results as standard SOUL $Datexxx functions, with additional enhancements.

    These string-format datetime $functions are available only with the Sir2000 User Language Tools.

    See Strict and non-strict format matching for a discussion of strict and non-strict format matching, including a technique for accomplishing strict date checking using the non-strict $functions.

See Errors in datetime $functions for information about error handling for datetime $functions.

Datetime formats

The string representation of a date is determined by a datetime format. This value is a character string, composed of the concatenation of these:

  • Tokens

    For example, YYYY for a four-digit year, and MI for minutes.

  • Separator characters

    For example, forward slash (/) in MM/DD/YY for two-digit month, day, and year separated by slashes.

These datetime format strings are used in several Rocket Model 204 add-on products in addition to Sir2000. The additional products using datetime format strings are:

The rules for these datetime format strings are consistent throughout all these products, though certain uses of these strings might impose extra restrictions. For example, a leading blank is allowed for the HH, DD, and MM parts of a date argument using a non-strict date $function (such as $Sir_Date2NS), but such a blank is not allowed for the strict date $functions (Sir2000 User Language Tools $functions).

Datetime format rules

Certain rules are applied to determine if a format is valid. The basic rules are:

  1. If a format string contains a numeric datetime token (that is, ND, NM, or NS), then the format string must consist of only one token. Numeric datetime tokens are supported only in format strings for the Sir2000 Field Migration Facility.
  2. You must specify at least one time, weekday, or date (except for Sir2000 Field Migration Facility alternate or error formats).
  3. Except for "weekday," you must not specify redundant information. More specifically this means:
    • Except for I, no token can be specified twice.
    • At most one year format (contains Y) can be specified.
    • At most one month format (contains MON, Mon, or MM) can be specified.
    • At most one day format (DD or Day) can be specified.
    • At most one weekday format (WKD, Wkd, WKDAY, or Wkday) can be specified.
    • If AM is specified, then PM cannot be specified.
    • At most one fractions-of-a-second format (contains X) can be specified.
    • If DDD is specified, then neither a day nor month format can be specified.
  4. If ZYY is specified in a format string, no other token that denotes a variable-length value may be used.
  5. If a format string contains other tokens that denote variable length values, then an * token may only appear as the last character of the format string.
  6. The DAY token may not be immediately followed by another token whose value may be numeric, regardless of whether the following token represents a variable length value. Thus, DAY may not be followed by *, I, YY, YYYY, CYY, MM, HH, MI, SS, X, XX, or XXX; DAY may not be followed by a decimal digit separator; and DAY may not be followed by a quote followed by a decimal digit.
  7. For non-Janus add-on products:

    When a pair of format strings are used for transforming date values, for example, for $Sir_DateCnv, #DATECNV, or processing of updates to fields that are connected by a SIRFIELD RELATE command, additional rules apply to the pattern matching tokens:

    • If one of the format strings includes one or more I tokens, then the other format string must contain the same number of I tokens. Note that the placement of I tokens within the format strings is not restricted. The I tokens are processed left to right, with each character from the input string that corresponds to the nth I token in the input format being copied unchanged to the character position in the output string that corresponds to the nth I token in the output format.
    • If one of the format strings contains an * token, then the other format string must also contain an * token. All of the characters from the input string that correspond to the * token in the input format, if any, are copied unaltered to the output string, beginning in the position that corresponds to the * token in the output format.
  8. The maximum length of a format string is 100 characters (except 31 for SirDBA).

Datetime format tokens

The valid tokens in a date format are shown in the following list. In general, the output format rule for a token is shown: that is, the result when a value from an SQL client is converted to operate on a DATETIME field, or the result when a DATETIME or SMALLDATETIME numeric value is converted to a datetime character string in a SOUL %variable.

The input format rules are less strict: for example, all of the tokens that convert from an alphabetic string (for example, MON) work with any case string (for example, jan or JAN or Jan).

For some of the functions, the input format rule for a token is the same as the output format rule; this is the definition of "strict date format matching." However, non-strict functions sometimes allow a string to match a token on input that would not be produced by that token on output.

All of the tokens that match alphabetic strings (for example, MON) match any case for non-strict matching. For other tokens that have differing strict and non-strict matching rules, usage notes for them are contained below in Datetime and format examples. Each input datetime format argument in the description of a function specifies whether the use of the format observes strict or non-strict format matching.

NM Numeric datetime value containing the number of milliseconds (1/1000 of a second) since January 1, 1900 at 12:00 AM. (This token is allowed only in the Sir2000 Field Migration Facility.)
NS Numeric datetime value containing the number seconds since January 1, 1900 at 12:00 AM. (This token is allowed only in the Sir2000 Field Migration Facility.)
ND Numeric date value containing the number of days since January 1, 1900. (This token is allowed only in the Sir2000 Field Migration Facility.)
* Ignore entire variable-length substring matching pattern, if any, only when retrieving a date value. Substitute with null string when only creating a date value. When copying date values, copy entire variable-length substring matching pattern, if any, from the input value to the location identified by * token in output string.
I For Janus products and SirDBA: ignore corresponding input character.

For other products: ignore corresponding input character when only retrieving a date value. Store a blank in corresponding output character when only creating a date value. When copying date values, copy each character matching an I token from from the input value to the location in the output string identified by the corresponding I token in the output format.

" Following character is "quoted," that is, it acts as a separator character.
YYYY 4-digit year
YY 2-digit year
CYY Year minus 1900 (3 digits, including any leading zero).
ZYY Year minus 1900, two-digit or three-digit year number, excluding any leading zero (variable length data).

Non-strict functions allow a three-digit number with leading zero on input, but any number less than 100 always produces a two-digit number on output. See Datetime and format examples.

MONTH Full month name (uppercase variable length).

For Janus products: if used as an argument to a method or $function for converting from a string, this is the same as Month.

Non-strict functions allow any mixture of uppercase and lowercase on input, but all-uppercase is always produced on output.
Month Full month name (mixed-case variable length).

For Janus products: if used as an argument to a function for converting from a string, this is the same as MONTH.

Non-strict functions allow any mixture of uppercase and lowercase on input, but initial uppercase letter followed by all lowercase is always produced on output.
MON Three-character month abbreviation (uppercase).

For Janus products: if used as an argument to a function for converting from a string, this is the same as Mon.

Non-strict functions allow any mixture of uppercase and lowercase on input, but all-uppercase is always produced on output.
Mon Three-character month abbreviation (mixed case).

For Janus products: if used as an argument to a function for converting from a string, this is the same as MON.

Non-strict functions allow any mixture of uppercase and lowercase on input, but initial uppercase letter followed by all-lowercase is always produced on output.
MM Two-digit month number.

For Janus products: if used as an argument to a function for converting from a string, this is the same as BM (leading blank is allowed).

Non-strict functions allow a two-character number with leading blank on input, but two decimal digits are always produced on output.

Note: A common mistake is to use MM instead of MI for minutes.

BM Two-character month number.

For Janus products: if used as an argument to a function for converting from a string, this is the same as MM. If less than 10, first character is blank.

Non-strict functions allow a two-digit number with leading zero on input, but any number less than 10 always produces a blank followed by a decimal digit on output.
DDD Three-digit Julian day number.
DDTwo-digit day number.

For Janus products: if used as an argument to a function for converting from a string, this is the same as BD (leading blank is allowed).

Non-strict functions allow a two-character number with leading blank on input, but two decimal digits are always produced on output.
BD Two-character day number. If less than 10, first character is blank.

For Janus products: if used as an argument to a function for converting from a string, this is the same as DD.

Non-strict functions allow a two-digit number with leading zero on input, but any number less than 10 always produces a blank followed by a decimal digit on output.

DAY One-digit or two-digit day number (variable length data).

Non-strict functions allow a two-digit number with leading zero on input, but any number less than 10 always produces a one-digit number on output.

WKDAY Full day of week name (upper case variable length).

For Janus products: if used as an argument to a function for converting from a string, this is the same as Wkday.

Non-strict functions allow any mixture of uppercase and lowercase on input, but all-uppercase is always produced on output.
Wkday Full day of week name (mixed-case variable length).

For Janus products: if used as an argument to a function for converting from a string, this is the same as WKDAY.

Non-strict functions allow any mixture of uppercase and lowercase on input, but initial uppercase letter followed by all-lowercase is always produced on output.
WKD Three-character day of week abbreviation (uppercase).

For Janus products: if used as an argument to a function for converting from a string, this is the same as Wkd.

Non-strict functions allow any mixture of uppercase and lowercase on input, but all-uppercase is always produced on output.
Wkd Three-character day of week abbreviation (mixed case).

For Janus products: if used as an argument to a function for converting from a string, this is the same as WKD.

Non-strict functions allow any mixture of uppercase and lowercase on input, but initial uppercase letter followed by all-lowercase is always produced on output.
HH Two-digit hour number.

Non-strict functions allow a two-character number with leading blank on input, but two decimal digits are always produced on output.

For Janus products: if used as an argument to a function for converting from a string, this is the same as BH (leading blank is allowed).
BH Two-digit hour number. If less than 10, first character is blank.

For Janus products: if used as an argument to a function for converting from a string, this is the same as HH.

Non-strict functions allow a two-digit number with leading zero on input, but any number less than 10 always produces a blank followed by a decimal digit on output.
MI Two-digit minute number.

Note: A common mistake is to use MM instead of MI for minutes.

SS Two-digit second number.
X Tenths of a second.
XX Hundredths of a second.
XXX Thousandths of a second (milliseconds).
AM AM/PM indicator.
PM AM/PM indicator.

Datetime format separators

The valid separators in a date format are:

  • blank
  • apostrophe (')
  • slash (/)
  • colon (:)
  • hyphen (-)
  • back slash (\)
  • period (.)
  • comma (,)
  • underscore (_)
  • left parenthesis ( ( )
  • right parenthesis ( ) )
  • plus (+)
  • vertical bar (|)
  • equal (=)
  • ampersand (&)
  • at sign (@)
  • sharp (#)
  • the decimal digits (0 - 9).

In addition, any character may be a separator character if preceded by the quoting character (").

See Datetime and format examples for examples that include the use of various separator characters.

Valid datetimes

For a datetime string to be valid it must meet the following criteria:

  • Its length must be less than 128 characters.
  • It must be compatible with its corresponding format string.
  • It must represent a valid date and/or time.

    For example, at most 23:59:59.999 for a time, 01-12 for a month, 01-31 or less (depending on the month) for a day. February 29 is only valid in leap years (only centuries divisible by 4 are leap years: 2000 is but neither 1800, 1900, nor 2100 are).

    Note: Weekdays are not checked for consistency against the date. For example, both Saturday, 02/15/97 and Friday, 02/15/97 are valid.

  • It must be within the date range allowed for the corresponding format.

    A datetime string used with a CYY or ZYY format can only represent dates from 1900 to 2899, inclusive. A datetime string used with a YY format can only represent dates in a range of 100 or less years, as determined by CENTSPAN and SPANSIZE (described below). The valid range of dates for all other formats is from 1 January 1753 thru 31 December 9999.

Processing dates with two-digit year values

A date field with only two digits for the year value is capable of representing a range of up to one hundred years. When we compare a pair of two-digit year values, we are accustomed to thinking of the century as fixed, so that all dates are either 19xx or 20xx. However, a date field with two-digit year values can actually represent dates from two different centuries, provided that the range of dates does not exceed 100 years.

Using CENTSPAN

CENTSPAN provides a mechanism for unambiguously converting dates with two-digit year values into dates with four-digit year values. The CENTSPAN mechanism allows two-digit year values to span two centuries without confusion. CENTSPAN identifies the four-digit year value that is the start of a range of years represented by the two-digit year values.

CENTSPAN may be specified as an absolute unsigned four-digit value between 1753 and 9999, or it may be specified as a relative signed value between -99 and +99, inclusive. A relative CENTSPAN value is dynamically converted to an effective absolute value before it is used to perform a YY to YYYY conversion. The effective CENTSPAN value is formed by adding the relative CENTSPAN to the current four-digit year value at the time the relative value is converted.

A simple algorithm is used to convert a two-digit year value (YY) to a four-digit year value, using a four-digit absolute or effective CENTSPAN value (HHLL). If the two-digit year value is less than the low-order two digits of the CENTSPAN value, then the resulting century is one greater than the high-order two digits of the CENTSPAN value. Otherwise the resulting century is the same as the high-order two digits of the CENTSPAN value.

Using all one hundred available years for mapping two-digit year values can cause significant confusion and result in data integrity errors. This is because dates just above and just below the 100-year window are mapped to the other end of the window. From the previous example, the date "47" will be interpreted as 1947, when it could have conceivably been 2047. Simlarly, the date "46" will be interpreted as 2046, when it might have been 1946.

If CENTSPAN is set to a value that is too high, dates that are just prior to CENTSPAN will appear to occur 100 years hence. If CENTSPAN is set to a value that is too low, dates that fall just after CENTSPAN+99 will appear to have occurred 100 years earlier. A full one-hundred year window also can not detect attempts to represent more than one hundred years of values with a two-digit year.

Using SPANSIZE

To protect from the ambiguities that can occur at each end of the 100-year window defined by CENTSPAN, SPANSIZE is used to restrict the size of the window used for mapping two-digit year values. The effect is to create two guard bands', one just below the date window and one just above. An attempt to represent a date value that lands in a guard band produces an error.

Each guard band contains CENTSPAN - SPANSIZE years, hence a SPANSIZE of 100 removes the protection. The default SPANSIZE is a value that you can customize in your load module. If you do not customize it, the value of SPANSIZE is 90, which provides protection for two ten-year windows: one below the CENTSPAN setting and one starting at CENTSPAN+90. From the previous example:

An attempt to represent the values "37" through "46" is rejected. This protects the range 1937 through 1946 as well as the range 2037 through 2046. Note that an intended value of 2047, expressed as "47" will be accepted and interpreted as 1947. In general a smaller SPANSIZE provides the highest assurance of correct mappings. However, any setting of SPANSIZE less than 100 will probably detect the case where a range greater than one hundred years is being used.

Strict and non-strict format matching

As mentioned in Datetime formats, for some of the $functions, the input format rule for a token is the same as the output format rule. This is the definition of "strict date format matching." However, non-strict $functions sometimes allow a string to match a token on input that would not be produced by that token on output.

The types of strict matching are as follows:

Alpha tokens For alphabetic tokens (for example, Month), a strict match requires the input value to be the correct case. For example, the MON token is strictly matched by JAN but not by Jan, and the reverse is true for the Mon token. For non-strict matching, the alphabetic tokens are matched by any combination of uppercase and lowercase input.
HH, MM, DD For these tokens, a strict match requires a leading zero for values less than 10. For non-strict matching, a value less than 10 can also be represented by a leading blank followed by a single numeric digit.
BH, BM, BD For these tokens, a strict match requires a leading blank for values less than 10. For non-strict matching, a value less than 10 can also be represented by a leading zero followed by a numeric digit.
DAY For this token, a strict match requires a single digit for values less than 10. For non-strict matching, a value less than 10 can also be represented by a leading zero followed by a numeric digit.
ZYY For this token, a strict match requires two digits for values less than 100. For non-strict matching, a value less than 100 can also be represented by a leading zero followed by a two numeric digits.

The strict functions are available only with the Sir2000 User Language Tools. If you want to use non-strict date $functions to check a datetime string using strict rules, you can use the following technique:

If date Eq '' Or date NE $Sir_NM2Date(- $Sir_Date2NM(date, fmt), fmt) Then error handling End If

Datetime and format examples

There is an extensive set of format tokens, as shown in Datetime format tokens. These tokens and the various separator characters can be combined in almost limitless possibility, giving rise to an extremely large set of datetime formats. This section provides examples of some common datetime formats, and it also tries to explain the use of some of the format tokens that might not be obvious.

This section also has examples for formats used with Sir2000 Use Language Tools that differ from their usage with other Model 204 products. These are noted in the examples.

Each example format is explained and is also presented with some matching datetimes, demonstrating only a few of the very many ways these tokens can be combined. It is assumed that these examples are invoked sometime between the years 1998-2040, as the basis for relative CENTSPAN calculations.

YYMMDD This is the common six-digit date format which supports sort order if all dates are within a single century.

The following SOUL code fragment prints the value OK:

If $sir_date2nd('960229', 'YYMMDD') > -9E12 Then Print 'OK' End If

For Sir2000 User Language Tools users, the following statement prints the value 1:

print $sir_datechk('YYMMDD', '960229')

YYYYMMDD This is the common eight-digit date format which supports sort order with dates in two centuries.

The following SOUL code fragment prints the value 19921212.

%n = $sir_date2nd('921212', 'YYMMDD') Print $sir_nd2date(%n, 'YYYYMMDD')

For Sir2000 User Language Tools users, the following statement prints the value 19921212:

print $sir_datecnv('YYMMDD', 'YYYYMMDD', '921212')

MM/DD/YY This is the U.S. six-digit date format for display. The value 12/14/97 matches this format.

The following SOUL code fragment prints the value OK:

If $sir_date2nd('12/14/94', 'MM/DD/YY') > -9E12 Then Print 'OK' End If

For Sir2000 User Language Tools users, the following statement prints the value 1:

print $sir_datechk('MM/DD/YY', '12/14/94')

Note: With non-strict format matching, such as $Sir_Date2nd, the leading zero corresponding to an MM token may be given as a blank, thus allowing " 7/15/98".

With strict matching, however, such a leading blank is not allowed for MM. A leading blank month value with a strict $function (that is, one of the Sir2000 User Language Tools $functions) requires the BM token.

If the data contains leading zeroes in some month instances and leading blanks in others, you must use a non-strict $function.

DD.MM.YY This is a European six-digit date format for display. The value 14.12.97 matches this format.

The following SOUL code fragment prints the value OK:

If $sir_date2nd('14.12.94', 'DD.MM.YY') > -9E12 Then Print 'OK' End If

For Sir2000 User Language Tools users, the following statement prints the value 1:

print $sir_datechk('DD.MM.YY', '14.12.94')

Note: With non-strict format matching, such as $Sir_Date2nd, the leading zero corresponding to a DD token may be given as a blank, thus allowing " 1.01.00".

With strict matching, however, such a leading blank is not allowed for DD. A leading blank day value with a strict $function (that is, one of the Sir2000 User Language Tools Functions) requires the BD token.

If the data contains leading zero days in some instances and leading blanks in others, you must use a non-strict $function.

Wkday, DAY Month YYYY "A"T HH:MI This is a format that could be used for report headers.

The following SOUL statement prints a value like Friday, 7 February 1998 AT 21:33:

print $sir_date('Wkday, DAY Month YYYY "A"T HH:MI')

Note:

  • If an input format contains AM or PM, then the time (HH:MI) must be between 00:01 and 12:00, and it must be accompanied by either AM or PM.
  • If an input format contains DAY (for example, DAY MON YY) with non-strict format matching, such as $Sir_Date2nd, the string matching it may have a leading zero, thus allowing 06 MAY 98.

    With strict matching $functions (that is, one of the Sir2000 User Language Tools $functions) however, such a leading zero is not allowed for DAY; a single digit must be supplied for days 1 through 9.

  • If an input format contains HH with non-strict format matching, such as $Sir_Date2nd, the string that matches it may have a leading blank, thus allowing " 8:30".

    With strict matching, however, such a leading blank is not allowed for HH; a leading blank hour value with a strict $function requires the BH token.

    If the data contains leading zero hours in some instances and leading blanks in others, you must use a non-strict $function.

YYIIII This format might be used for data that contains a two-digit year prefixing other information, such as a sequence number. The value 92A123 matches this format.

The following SOUL code fragment prints the value 02:

%d = $sir_date2nd('92ABCD', 'YYIIII') Print $sir_nd2date(%d + 10*365.25, 'YY')

For Sir2000 User Language Tools users, the following statement prints the value 1992ABCD:

print $sir_datecnv('YYIIII', 'YYYYIIII', '92ABCD')

Note: When a pair of format strings are used for transforming date values, for example for $Sir_DateCnv or processing of updates to SIRFIELD RELATE fields, both formats must have the same number of I tokens. The $functions with both an input and output format, for example $Sir_DateCnv, are only available in the Sir2000 User Language Tools; SIRFIELD is part of the Sir2000 Field Migration Facility.

YY* This format might be used for data that contains a two-digit year prefixing other information, such as a sequence number, when the other information is variable length. The values 92 and 92ABC123 match this format.

The following SOUL code fragment prints the values OK and OK:

If $sir_date2nd('92', 'YY*') > -9E12 Then Print 'OK' End If IF $sir_date2nd('1992ABC', 'YYYY*') > -9E12 THEN Print 'OK' End If

For Sir2000 User Language Tools users, the following statements print the values 1992 and 1992XYZ:

print $sir_datecnv('YY*', 'YYYY*', '92') print $sir_datecnv('YY*', 'YYYY*', '92XYZ')

Note:

  • At most one occurrence of the asterisk (*) token may appear in a datetime format.
  • If a pair of format strings are used for transforming date values, for example for $Sir_DateCnv or processing of updates to SIRFIELD RELATE fields, then if a * token appears in one of the formats, a * must also appear in the other format.

    The $functions with both an input and output format, for example $Sir_DateCnv, are only available in the Sir2000 User Language Tools; SIRFIELD is part of the Sir2000 Field Migration Facility.

CYYDDD This is a compact six-digit date format with explicit century information, from 1900 through and including 2899. The value 097031 (representing 31 January 1997) matches this format.

The following SOUL fragment prints the value OK:

If $sir_date2nd('097031', 'CYYDDD') > -9E12 Then Print 'OK' End If

For Sir2000 User Language Tools users, the following statement prints the value 1:

print $sir_datechk('CYYDDD', '097031')

ZYYMMDD This is a compact six- or seven-digit date format with explicit century information, from 1900 through and including 2899, that can often be used with "old" YYMMDD date values in the 1900s. The values 970501 (representing 1 May 1997) and 1000501 (representing 1 May 2000) match this format.

The following SOUL fragment prints the values OK and OK:

* Check 1 Dec, 1997: If $sir_date2nd('971201', 'ZYYMMDD') > -9E12 Then Print 'OK' End If * Check 1 Dec, 2000: If $sir_date2nd('1001201', 'ZYYMMDD') > -9E12 Then Print 'OK' End If

For Sir2000 User Language Tools users, the following statements print the values 1 and 1:

* Check 1 Dec, 1997: print $sir_datechk('ZYYMMDD', '971201') * Check 1 Dec, 2000: print $sir_datechk('ZYYMMDD', '1001201')

Note: With non-strict format matching (such as $Sir_Date2nd), a three-digit number with a leading zero may correspond to a ZYY token, thus allowing "0971201".

With strict matching, however, a three-digit value with a leading zero is not allowed for ZYY. A three-digit value less than 100 with a strict $function (that is, one of the Sir2000 User Language Tools Functions) requires the CYY token.

If the data contains values less than 100 as three digits in some instances and as two digits in others, you must use a non-strict $function.

YY0000 Decimal digits can be used as separator characters. The value 980000 matches this format.

The following SOUL fragment prints the value 1992NA:

%n = $sir_date2nd('92000', 'YY000') Print $sir_nd2date(%n, 'YYYY"N"A')

For Sir2000 User Language Tools users, the following SOUL statement prints the value 1992NA:

Print $sir_datecnv('YY0000', 'YYYY"N"A', '920000')

Note: Numeric separators, unlike alphabetic separators, do not need to be preceded by a double-quote character (").

CENTSPAN argument of $Sir_Datexxx functions

Many of the $Sir_Datexxx functions accept an optional argument containing a CENTSPAN value to be used for the call. The default value of any CENTSPAN argument is -50, excepting the $Web_Date2xx functions without a format argument, in which case the CENTSPAN argument is ignored and a CENTSPAN of 1990 is used. The default value should be adequate in most cases. If you carefully determine it should be different in some application, code the value on the relevant $function invocations.

For a different approach, see the description of the CENTSPLT and DEFCENT parameters and $function arguments.

Benefits of Sir2000 datetime processing

Following is a list of benefits offered by Sir2000 and $Sir_Datexxx datetime processing. To provide concrete comparisons, there are some references to the standard SOUL date $functions.

SPANSIZE The SPANSIZE processing creates a very strong barrier to detecting otherwise unnoticed two-digit year processing errors.
Relative CENTSPAN The relative CENTSPAN specification (for example, -50) lets you maintain a flexible "rolling" window for two-digit year processing.
Default CENTSPAN One significant advantage of a relative CENTSPAN is that it allows the default (1990 for $Web_Date2xx functions without a format, and -50 otherwise) of a reasonable value without parameter changes in all batch and Online jobs.
Format tokens There is a very large set of tokens in the Sir2000 and $SirDatexxx datetime formats. For example, there are four different tokens representing the day of the week, and time of day can be represented. Standard SOUL date formats do not have any day-of-week or time-of-day tokens, and other standard SOUL token variations, for example, CYY versus ZYY, are done by a complex argument setting.
Pattern match tokens The Sir2000 and $SirDatexxx datetime formats can contain single-character (I) or variable-length character (*) match-any tokens in datetime formats. For example, you can specify that a string has an embedded year, and you can process that year as a date.
Format-free representations Non-string datetime values allow you to pass around dates simply as numbers, without the complexities of carrying the corresponding string format (you only need to establish the scale to operate on a value).
Operating on numeric representations Numeric date values can be operated on directly with SOUL, especially allowing you to add datetime differences (for example, +), rather than calling a $DateChg $function and providing a format.
Time All Sir2000 and $SirDatexxx datetime $functions allow any reference to a "date" to include time of day. The only standard SOUL datetime $function that provides a time of day is $Time, the current time of day, in one fixed format.
$Sir_Date formats $Sir_Date lets you specify any format to return the current date and time. $Date has only a few numeric codes for a few formats.
Error control arguments Sir2000 User Language Tools provides error handling control that applies to all datetime $functions, including standard SOUL. Additionally, the Sir2000 and $SirDatexxx datetime $functions (except $Sir_DateFmt) let you specify error control for a single $function invocation.
Error values of numeric date $functions The $functions that use non-string datetime values provide very uniform error return values: -9.E12 or a null string, for numeric or string result $functions, respectively.

See also