One small thing that comes and goes: if you merge two files, some variable names in the merged file come through rudimentary, eg

freq sex

of patient N Female 226 Male 271 Missing 94 Total 591

but correct with:

freq sex /vnl

sex of patient N Female 226 Male 271 Missing 94 Total 591

Not a really problem, just a small thing to perhaps look at, and not for all field names.

Hans