Doug,

I published a tech note explaining how dynamic files actually work a while ago, also part of that document is understanding the limitations of memresize and the differences v resize. 

Please read the attached it should cover what you are asking and more.

For reference due to the limitations of memresize around dymanic files I use resize far more often than I do memresize.

Regards,

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Jonathan Smith
UniData ATS
Rocket Support
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