My regex not working with work flow validator

[Nannette Mori]

I want to validate that users are entering a classification before there summary text.

So I want to check if the summary starts with (U) or (S) or (TS)

for my regex I input 

^([US])* or (TS)*

this doesn't seem to work.  The error displays even after I have entered one of the classifications.

ex:  summary would be (U) This is my Summary. If it didn't contain (U) it should throw an error.

Is my regex not correct?

[Subrat Mishra · Accepted solution]

^(?:U|S|TS).*

[Vikrant Yadav · Accepted solution]

Hi @Nannette Mori  Try to use | instead of or

^([US])* | (TS)*

[Subrat Mishra]

^(?:U|S|TS).*