I was learning Laws of the Game from IFAB  [official website](http://www.theifab.com/laws) and have a question about the technical area.

In the [Laws](http://www.theifab.com/laws/the-field-of-play/chapters/the-technical-area), it states as follows:

> ### 9. Technical Area
> ...
>
> the occupants of the technical area:
>
> - are identified before the start of the match in accordance with the competition rules
> - must behave in a responsible manner
> - _must remain within its confines except in specific circumstances, e.g. physiotherapist/doctor entering the field of play, with the referee’s permission, to assess an injured player_

Look at the third item in italic font. I don't see it clearly states about substitutes. I see substitution players do warm-up during the match, in the area along the touchlines outside of the technical one. Is anything mentioned about this clearly in other chapters?