En terrasse vs sur la terrasse

Question

Hello - in the exercise it says:.....on a bu notre café sur la terrasse.

Further down in the Q&A, White asked about the difference between 'sur la terrasse' and 'en terrasse'.

Céline's answer seems to suggest that the exercise above is incorrect.

Have I understood correctly i.e. saying 'sur la terrasse' implies that something is actually physically on the terrace and so in effect, the extract should read: .... on a bu notre café en terrasse. ( One would assume that they were sitting on chairs on the terrace and not directly on the surface of the terrace as would be the case of a pot plant etc as per Céline's examples.)

If my understanding is correct, should the exercise not be corrected to say 'en terrasse' instead of 'sur la terrasse' ?

Accepted Answer

Belinda , ‘en terrasse’ as a fixed expression is used for ‘commercial’ premises - restaurants etc -  but ‘sur la terrasse (de notre maison)’. See definition from wordreference of ‘en terrasse’.
 https://www.wordreference.com/fren/en%20terrasse 
The ‘terrasse’ for a restaurant is not necessarily a patio/balcony, but a more abstract ‘lieu’.
https://www.wordreference.com/fren/terrasse
From discussion on wordreference there may be some regional differences though, at least between countries :
 https://forum.wordreference.com/threads/fr-dans-sur-en-à-la-terrasse.2977502/

Answer

Cancelled -- already acknowledged previous discussion.