utility to rename existing fields
Useful, for example, to change a
U field for further calculation (ref: EP523)
if required in the future, could have a generalized rename utility (with regular expressions and placeholders etc), but for the current requirements a simple small set of pre-defined methods should be sufficient.
s/^(.+)Mean/$1/; # Renames existing target as $1.orig
These predefined actions are obviously less flexible than regex support, but presumably also user friendlier.