How to use format-string "Sx" in function @Text and @TimeToTextInZone?

Example @Text(@Now; “Sx”) return error message “Unrecognized data/time STRUCTURE format specifier”.What sense in use of the given parameter? What components should be present at returned value?

In Help about format-string “Sx” in function @Text and @TimeToTextInZone it’s written:

Sx — Use when you cannot predict the exact format of the value being passed, but you know that it will be either a time, a date, or both.

Subject: Question is closed

I have understood, that Sx it’s only a mask.