[Groff] groff ms: Is there an order to setting PS and VS versus PO and LL

[Dorai Sitaram]

If I set  registers PO and LL and also set PS and VS, the values of PO and LL 
seem to revert to the default values. It doesn't seem to matter which order I 
set these registers in (all done in the preamble of the document of course).  
What is a way to make all settings of these four registers stick?
thanks,--d