I have a JMP column with data where I would like to systematically add the same initial character to each entry.
Given a character column with the name "mycol" here is a script that will add the character "A" as the first character to the mycol column for each row
for each row( :mycol = "A" || :mycol; );
If you are comfortable with regex, you can use find/replace to do it; .* matches the content of each cell and \0 refers to the entire match.
Recode can also be used for this with Replace String
You can also do this by using new formula column and replace data in place