What does the 's' of Twilio API's sid stand for?

Question

In Twilio's API docs, sid is frequently used, for example, workflowSid.

Does the sid means secure id or not?

I did some search with no obvious answer.

Could anyone please point out what does sid means?

Answer 1

Newer documentation says it stands for "String Identifier":

https://www.twilio.com/docs/glossary/what-is-a-sid

(This was bugging me too. It's not mnemonically helpful to see an acronym everywhere without a sensible meaning of what it is)

"String ID" will have to do!