Question : Word VBA - how to populate table column from custom 'formula'

Word VBA - I want to populate a column in a WORD table, using VBA code, i.e. when the previous 2 columns have been selected (from drop down lists) the 3rd column populates with the resulting string - dependent on what was selected in the pevious 2 columns. The three columns are all strings - so I can't use any WORD functions.
I know the VBA code - thats not the problem - just don't know how to get the code to execute when the either/both the first 2 columns are changed.
Is this do-able? If so, can you give me some pointers on how?  thanks

Answer : Word VBA - how to populate table column from custom 'formula'

MSSTD stands for Microsoft Standard form, don't know why it works both ways but I've also noticed that, although I had some instances where outlook did not work without the prefix.

as a side note I had trouble remembering this stupid prefix so now I remember it as :

MicroSoft Sexually Transmitted Disease :)