One Time Code format in SMS messages

Hi,


When I send SMS message with a one time code for my iOS app registraion what rules is iOS 12 using to parse the SMS message and recognise the code for Autofill?


Here are some things i noticed but can't find these written down anywhere in the documentation.


1. you have to put the word code in the SMS

2. the code must appear in the first sentence of the SMS.


Anyone know where these parse rules defined or is that published anywhere?


Thanks,


Patrick