NX Nastran DMAP Programmer's Guide - Kxcad.net

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Automatic Deletion of Scratch Data Blocks
1.7 Automatic Deletion of Scratch Data Blocks
Scratch NDDL and local data blocks are stored on the SCRATCH DBset (p. 16). A
DBset is a physical file that is a subdivision of the database. To minimize the size of
the SCRATCH DBset, module scratch files are automatically deleted upon completion
of the module and DMAP scratch data blocks are automatically deleted after the
DMAP instruction in which they are used last. The location of this DMAP instruction
is called the last-time-used (LTU). An LTU is assigned to every data block. When the
LTU of an Scratch NDDL data block is reached, the data block is deleted if the current
qualifier values match. If the data block’s LTU is skipped, then the entire family is
deleted, regardless of the current qualifier values.
Special rules apply for data blocks specified in the following situations:
• For a scratch data block specified before a loop and last used inside the loop,
the LTU is extended to the bottom of the loop (e.g, ENDDO), meaning that
the data block is deleted when the loop is exited. If the data block is Scratch
NDDL, the entire family is deleted, regardless of the current qualifier values.
• For a local data block created inside a DMAP loop and last used after the
loop, the data block is deleted after the next execution of the top of the loop,
e.g., DO WHILE, even though the data block’s LTU is located after the loop
(i.e., when the loop is exited). Thus, the last generated data block can be used
after the loop exits.
• For a scratch data block created and last used inside a DMAP loop, the FILE
statement with the SAVE keyword extends the data block’s original LTU to
the bottom of the loop; otherwise, the data block is deleted at the original
LTU within the loop.
• For a Scratch NDDL data block used in a DBVIEW statement, the data block
is deleted at the LTU of the view name or the data block name, whichever is
last.
DlAG 57 prints the LTU information of all data blocks and a message indicating when
they are deleted.