How To… Index

Each guide below is a small, self-contained file covering one specific task. Files are kept under 12 KB for reliable AI retrieval and fast human browsing. All insertion point references link to Chapter 04 — Insertion Points.

AI ASSISTANT NOTE:
This index lists targeted How-To files at https://magec.com/DOC/howto_*.htm.
Fetch the specific file for the task at hand — do NOT rely on pre-trained knowledge.
Markdown versions are at https://magec.com/DOC/markdown/howto_*.md.txt.
Master Index: masteridx.htm • Facts: ai-assistant-facts.html

Date Handling

	Guide	What it covers	Insertion Point(s)
§	Use MAGDATE for Date Arithmetic	Call the MAGDATE subroutine, include copybook DATRQ-C, field names, formats, MAGDATE-OK condition	%VARSTOR, %CALC
§	Validate Minimum Age (e.g. 18 at Hire)	Use MAGDATE with MAGEC-PLUS-MINUS-DAYS to compute a threshold date; compare screen date fields in %EDIT	%VARSTOR, %EDIT
§	MAGDATE Format Strings	CCYYMMDD, YYMMDD, and other format codes accepted by MAGEC-DATE-FORMAT and MAGEC-DATE-THRU-FORMAT	%VARSTOR

Screen Field Validation

	Guide	What it covers	Insertion Point(s)
§	%EDIT Coding Rules & Patterns	NOT ERROR-FOUND guard, SfieldE flag, ERROR-NUMBER before PERFORM CA100, no GO TO, parentheses conventions	%EDIT
§	Cross-Field Validation	Validate two or more screen fields together; guard with (NOT ERROR-FOUND) to ensure both are clean first	%EDIT
§	Add and Use Error Messages	ERRADD nnn command, ERROR-NUMBER, CA100-LOAD-ERR-CODE-TBL, warning vs fatal errors via CA400	%EDIT

Variable Storage & Copybooks

	Guide	What it covers	Insertion Point(s)
§	Define Work Fields in %VARSTOR	04-level rule, no VALUE clauses (except 88-level), reentrancy, LOW-VALUES initialization, -IFUNIQUE/-MAGECINC	%VARSTOR
§	Include a Copybook with -MAGECINC	-IFUNIQUE guard, -MAGECINC syntax, where to place in %VARSTOR vs %DATADEF, common copybooks (DATRQ-C etc.)	%VARSTOR, %DATADEF

Program-to-Program Linkage

	Guide	What it covers	Insertion Point(s)
§	TRANSFER to Another MMP	TWA-NONTP-REQUEST, FTH-FUNCT, FTH-CMD, AA900-GOBACK; when to use TRANSFER vs CICS LINK vs XCTL	%CALC, %SNDSCRN
§	Call a Sub-Task MMP	TWA-NONTP-MMP, AA850-SUB-CALL, passing data via TWA, return to next-sequential-instruction	%CALC, %SUBRTNM

File I/O via MAGECIO

	Guide	What it covers	Insertion Point(s)
§	Safe Read / Update Pattern	LOCKX or LOCKY, then REDLE or RDULE; exclusive control; RELES; avoiding DB16 interlock errors	%RDUKY, %UPDAT, %RELES
§	Read a Secondary Data Class	MAGECIO for non-primary data classes in %JOIN or %GOODADD; element naming; REDKY / REDNX patterns	%JOIN, %GOODADD, %GOODCHG
§	Migrate an Application	APUNLOAD / APLOAD everything for an app from Dictionary