Certificate of Authority to Transact Business from the Secretary of State's website
You're on the right track. Note that when you click "other" that you will open a 50 character field; you can't be too wordy. Also, be careful that your abbreviations would make sense to someone from a different state. Maybe:
SOS Cert. of Authority Dtd. XX/XX/XX
You can identify the issuing state in the following entry. Internally, I suggest you homogenize your descriptions so multiple BSA forms filed on behalf of the same customer say the same thing.