SNAX/HLS Application Programming Manual

Programming Constraints
Customization
104707 Tandem Computers Incorporated 7–3
TAL Copybook
Definitions
The TAL module, HLSDDT, contains definitions for the data structures needed by the
customization routines. You include these definitions in your TAL source code using
the following statement:
?SOURCE HLSDDT( USEREXITS )
To ensure that your data structures are compatible with those of the latest version of
SNAX/HLS, you are strongly discouraged from copying the supplied data structures
or defining them yourself. Subsequent releases of SNAX/HLS might require that you
recompile your customization routines, but you can probably leave your source
routines unchanged. Thus, you should retain the source form of your routines and
rely upon the source statement (as shown above) to obtain data structures and value
definitions.
Programming
Constraints
The customization routines can call quick system services (such as timer services,
name inquiries, and so on), but they cannot perform I/O operations on files known to
SNAX/HLS. They also should not perform I/O operations on other files, because
doing so would require WAIT I/O, which would slow down SNAX/HLS.