LS9 Rule creation on a character string

unknown

I need to check a field for a specific character string e.g. in the first n number of characters - is this possible?
Anyone know the format of the Rule (e.g. [field name, (starting character, ending character)])?

Birst TAM Solution Brief.pdf

VID005_ICSD_Adding a Dropdown and pointing to Part of a User Field.zip

unknown

Sure, I have many rules that do this. Use the subString function. Here's one example from HR55.1 to look only for a group name that starts with "BOS":
subString(form.PRG_GROUP_NAME,1,3)=='BOS')