The other thing that changes between walls is what's considered "in". Options I've seen have included:
i) only touch the coloured holds
ii) only touch the coloured holds with your hands, feet can use the coloured holds and any bits of wall ("features")
iii) hands and feet can use features and holds
...plus edge-cases regarding adjacent panels

My current wall's bouldering setup is such that there is no hint of grading, and routes are identified by holds of the same colour.

[is there a post of glee on the way?]