Specifying a previous revision number

[Daniel Yek]

Hi,

I'm wondering if there is an easier way to specify a (relative) previous 
revision of a file.

Currently, I'm doing a "cvs log", find the log, and then the associated 
revision number;
if the number end at ".2" or greater, it is easy to figure out the 
previous revision number -- just minus one from the last digit.

If the revision number is ".1", I'll have to find the previous branch 
revision number and that is several more steps to go through and can be 
error-prone.

Is there a way I can specify the previous revision number using the 
"@-1" or something similar?

For example, I'm looking for something likes this:
cvs diff -uw -r address@hidden -r 1.6.1.2.1 file.c

Or it can be a query command that, given a revision number of interest, 
returns the previous revision number.

Thanks.

--
Daniel.