FNVMASK parameter: Difference between revisions

From m204wiki
Jump to navigation Jump to search
No edit summary
No edit summary
 
(3 intermediate revisions by 2 users not shown)
Line 9: Line 9:
<dd>User 0 CCAIN parameters
<dd>User 0 CCAIN parameters
<dt>Related products
<dt>Related products
<dd>[[Sirius Performance Enhancements V3]]
<dd>[http://sirius-software.com/maint/download/perfr.pdf Sirius Performance Enhancements V3]
<dt>Introduced
<dt>Introduced
<dd>Before <var class="product">Sirius Mods</var> 6.7
<dd>Before <var class="product">Sirius Mods</var> 6.7
</dl>
</dl>
==Description==
==Description==
This is a single-byte bitmask parameter.
This is a single-byte bitmask parameter.
If set to a non-zero value, FNVMASK indicates the bytes in
If set to a non-zero value, <var>FNVMASK</var> indicates the bytes in
filenames that are not required to match those in the filenames on the physical
filenames that are not required to match those in the filenames on the physical
file pages.
file pages.
Bytes in filenames corresponding to the ON bits in FNVMASK do not have to
Bytes in filenames corresponding to the ON bits in <var>FNVMASK</var> do not have to
match the comparable bytes in the physical filenames.
match the comparable bytes in the physical filenames.


For example, if FNVMASK is set to X'10', the fourth byte of a filename
For example, if <var>FNVMASK</var> is set to X'10', the fourth byte of a filename
does not have to match the physical filename.
does not have to match the physical filename.
That is, you might be able to open a file with physical name FOOBAR as
That is, you might be able to open a file with physical name FOOBAR as
FOODAR, or FOOLAR, or FOOTAR.
FOODAR, or FOOLAR, or FOOTAR.
If FNVMASK were set to X'34', bytes 3, 4, and 5 wouldn't need to match, so
If <var>FNVMASK</var> were set to X'34', bytes 3, 4, and 6 wouldn't need to match, so
FOOBAR could be opened as FOOLER, or FOCKER, or FOLDER, to name just a few.
FOOBAR could be opened as FOOLAP, or FOCKAZ, or FOLDAR, or FOXBAG to name just a few.


FNVMASK facilitates sharing of data between Onlines, making it possible
<var>FNVMASK</var> facilitates sharing of data between Onlines, making it possible
for two files with the same physical name to be opened in the same Online
for two files with the same physical name to be opened in the same Online
by opening them under two different names that only differ in the bytes
by opening them under two different names that differ only in the bytes
indicated by FNVMASK.
indicated by <var>FNVMASK</var>.
This can be especially useful in moving procedures from one file to a
This can be especially useful in moving procedures from one file to a
like-named file to be used in a different Online.
like-named file to be used in a different Online.


'''Note:'''FNVMASK in no way alters the file-enqueuing behavior
<p class="note">'''Note:''' <var>FNVMASK</var> in no way alters the file-enqueuing behavior
of <var class="product">Model 204</var> &mdash; no file opened for update by one Online can be opened
of <var class="product">Model 204</var> &mdash; no file opened for update by one Online can be opened
by another, regardless of the name under which it is opened.
by another, regardless of the name under which it is opened. </p>


Use of <var>FNVMASK</var> does not weaken page trailer validation, as page trailer
validation at disk reads will validate the name against all bytes of
the physical file name, regardless of <var>FNVMASK</var>.


Use of FNVMASK does not weaken page trailer validation, as page trailer
validation at disk reads will validate the name against all bytes of
the physical file name, regardless of FNVMASK.
[[Category:System parameters]]
[[Category:System parameters]]
[[Category:Parameters]]
[[Category:Parameters]]

Latest revision as of 10:50, 21 May 2015

Filename version mask

Summary

Default value
X'00'
Parameter type
System
Where set
User 0 CCAIN parameters
Related products
Sirius Performance Enhancements V3
Introduced
Before Sirius Mods 6.7

Description

This is a single-byte bitmask parameter. If set to a non-zero value, FNVMASK indicates the bytes in filenames that are not required to match those in the filenames on the physical file pages. Bytes in filenames corresponding to the ON bits in FNVMASK do not have to match the comparable bytes in the physical filenames.

For example, if FNVMASK is set to X'10', the fourth byte of a filename does not have to match the physical filename. That is, you might be able to open a file with physical name FOOBAR as FOODAR, or FOOLAR, or FOOTAR. If FNVMASK were set to X'34', bytes 3, 4, and 6 wouldn't need to match, so FOOBAR could be opened as FOOLAP, or FOCKAZ, or FOLDAR, or FOXBAG to name just a few.

FNVMASK facilitates sharing of data between Onlines, making it possible for two files with the same physical name to be opened in the same Online by opening them under two different names that differ only in the bytes indicated by FNVMASK. This can be especially useful in moving procedures from one file to a like-named file to be used in a different Online.

Note: FNVMASK in no way alters the file-enqueuing behavior of Model 204 — no file opened for update by one Online can be opened by another, regardless of the name under which it is opened.

Use of FNVMASK does not weaken page trailer validation, as page trailer validation at disk reads will validate the name against all bytes of the physical file name, regardless of FNVMASK.