Best method I know of is
TextFormatRemove ( Self )
By using "self", you have a single expression you can now copy and paste into the auto-enter calculation of each of your fields.
But keep in mind that there is one key distinction between ctrl-shift-V and the auto enter calculation. With the auto-enter calc, it is impossible for the user to ever apply text formats to the text in the field--whether by using the tools in the formatting tool bar or by pasting formatted text. With the keyboard shortcut, you give the users an option to paste with or without the formatting.
Hmmm, now that I think about this, you could set a script to run from an OnRecordCommit trigger that used go to next field to loop through all the fields in your layout's tab order and use set field by Name to strip out the text formatting. That might be less work for you the developer than setting this up on each individual field, but also might have create a small delay each time the record is committed.
Most of our layouts are used for printing, so complete control over text format is required.
I will look into the trigger but before, I will have to catch up on FileMaker changes: I introduced FM to our company back when V4 was out (1998) and haven't been involved since then...
Thanks for the tip!