Is it possible to set up the mask to work with the following scenario?

Is it possible to set up the mask to work with the following scenario?
We have membership numbers in the format: @@-#####-@ AND @@-#####-@@
As you can see, the last section of the membership number can be 1 or 2 letters.
I can't seem to set up the mask to accept both of those options. Only one or the other.

As far as I can see, the input mask works are per your requirement on the Short text field.

Here is an example:

Do try and let us know. If there is still an issue, please let us know how different it is working at your end.

The help that gerardw left above does not solve the problem. That mask requires 2 alphabetical characters following the final hyphen. In the original question, they need it to accept EITHER 1 or 2 characters in this location.

The actual answer is to use square brackets, an instruction that is missing from the explanation.

To accept entries in the format @@-#####-@ and @@-#####-@@ you need to enter @@-#####-@[@] in the input mask field.

Sorry for the confusion. I may have overlooked the "or" that you mentioned in your first response.

I understand that you want either of the formats on the same field using input masking.

Yes, usage of square brackets is possible as you have mentioned.

Glad to know that you were able to resolve it.