Thanks. Once I allowed for inconsistencies in the nomenclature I saw what I 
needed.

--
Shmuel (Seymour J.) Metz
http://mason.gmu.edu/~smetz3
עַם יִשְׂרָאֵל חַי
נֵ֣צַח יִשְׂרָאֵ֔ל לֹ֥א יְשַׁקֵּ֖ר



________________________________________
From: IBM Mainframe Assembler List <ASSEMBLER-LIST@LISTSERV.UGA.EDU> on behalf 
of Jonathan Scott <jonathan_sc...@vnet.ibm.com>
Sent: Saturday, November 2, 2024 8:41 AM
To: ASSEMBLER-LIST@LISTSERV.UGA.EDU
Subject: Re: Offsets in ADATA

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Shmuel (Seymour J.) Metz writes:
> The mapping for ADATA has a number of fields described as offset without
> saying what they are offsets against. It appears as if the answer varies
> depending on the record type. Is there a guide to parsing ADATA that spells
> it out?

Although the comments in the ASMADATA macro are intended to be
helpful, they do not provide full documentation.  The official
interface information for the ADATA records is in the section
"Associated data file output" in the Programmer's Guide, which
has separate topics for each record type:

https://www.ibm.com/docs/en/hla-and-tf/1.6?topic=output-associated-data-file

Unless stated otherwise, offsets are normally relative to the
start of the record.  This means the complete record as written
to the data set, including the 4-byte V-format length prefix.
(On VM/CMS, the length prefix is removed by the QSAM simulation
routines and the length is stored outside the record, so if the
file is read using CMS access methods, the offset is 4 more than
the offset from the start of the CMS record).

If you spot any case where the documentation does not match the
implementation, please let us know.

Jonathan Scott, HLASM
IBM Hursley, UK

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