Putting the USING with the DSECT is not very good practice.  USING and DROP 
statements should normally be used at the start and end of ranges of source 
statements where it is valid for the assembler to use the relevant mapping, so 
that the assembler has specific information to check against, and can detect 
errors, for example where a DSECT field is referenced before the register is 
set up or after it is no longer valid.  Asserting that the register always 
points to that DSECT is another example of telling a lie to the Assembler, 
which is generally a bad idea.

Jonathan Scott

-----Original Message-----
From: IBM Mainframe Assembler List <[email protected]> On Behalf 
Of David Clark
Sent: 11 February 2026 19:53
To: [email protected]
Subject: Re: [External Sender] Re: Move data to a location prior to a given 
(based) address

1.  Because it works perfectly.  And it works because the DSECT isn't 
referenced until after R10 has been set.
2.  Because R10 is set/reset in multiple places because multiple incoming 
parameters, of the same layout, are being passed to the subroutine.
3.  Because showing it in direct association with the DSECT it references is 
more visible and intuitive (at least, to me, and I'm all that matters).

Sincerely,

Dave Clark
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On Wed, Feb 11, 2026 at 2:39 PM Seymour J Metz <[email protected]> wrote:

> Then why is the USING with the DSECT instead of the code it belongs with?

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