gtpa2m3hApplication Programming

Data Control

This field is used to specify the record size and whether 2 standard chaining fields are to be used.

Program ID

Upon filing a record, the system inserts the 4-byte system name of the program requesting the file operation. For C programs, this is the name of the first external function. Use of the optional NOTAG parameter on file functions bypasses the TPF system code that places the program identification in the record header. This parameter should only be used when the application updating the record has placed the required program identification in the header directly.

Chaining Addresses

Standard forward and backward chaining address fields may be used to link records together. Complex data structures may, of course, be created by chains in the data content of the record. The use of the standard chain fields permits common system routines to do integrity checks on data chains. (This idea is used to recover unreturned or lost pool records, a process called RECOUP).