[HECnet] RSX-11 SYSGEN (NOOB) QUESTION

Hi All, I've dusted off my PiDP11/70 running RSX-11M+ (v4.6). Anyway the "stock" image that came from the PiDP site is not to my taste so I've been trying to customise it. Nothing fancy just changing the system name from the standard "PiDP11" to "WITHER". I should stress that I am an utter noob and have zero experience with RSX-11 so doubtless I will use the wrong terms and I know my issues are due to that lack of understanding. To make my life easier with SYSGEN I was using the existing answer files (SYSGENSA1.CMD, etc) and simply editing the items I want. The trouble is, generating a system with these files is producing a system image that has a very small secondary pool (SECPOL). That then produces various errors with commands grumping that there is insufficient SECPOL.... I have figured out how to expand the secondary pool from the command line (which prevents any grumping) but I would like to permanently fix the situation. From the documentation that I've read, and as I understand it, I should be able to pause the SYSGEN and edit files manually mid-generation. In this case I should be able to edit the "SYSVMR.CMD" which is generated at an earlier phase within SYSGEN and then continue the SYSGEN which will then utilise the file (SYSVMR.CMD) in one of the later phases . Except, it does not seem to work. Editing the SYSVMR.CMD file prior to starting SYSGEN clearly overwrites the changes during an early stage. Pausing the SYSGEN and editing the SYSVMR.CMD file mid-generation does retain the settings but does not appear to make any difference to the final image. By way of  a little more explanation. I'm presuming once I've "paused" the SYSGEN all I need to do is EDT the SYSVMR.CMD file (in other words, I'm not doing anything further, running any other commands or what-not). All I'm doing is editing the SYSVMR.CMD file (specifically the "SET /PAR=SECPOL" line), and restarting the SYSGEN with "UNS AT.<ESC>". I presuming I am missing out either a vital step or command or completely misunderstanding the "set /par=secpol" line. Any pointers gratefully received Mark