The subs command uses variables assigned to values that sub into an equation so the original equation being subbed into is not changed.  Wouldn't it be nice to assign variables during a subs command as well?  I don't really think it adds any value but it would make the command a little more versatile. 

As an example subs({G:=6.67e-11,M:=1.99e30,m=5.98e24,r=1.496e11},F);   Then I suppose one would say you could just pull those assigned variables right out of the subs command.  G is a constant anyway but the assigned M could be pulled out..............hmm I seem to have lost my thought, I'm not sure why or where something like that (assigning variables in a subs command) would or could be useful.   

I suppose I could just create a new command in a library called subs1 that does that (not exactly sure how I would go about creating that new subs command) but it could be done.  Maybe someone could point out to me how to do this?  Is that useful or perhaps it's too redundant to be bothered with?