| description: |
Used to make a category be 'used' by references of the type query, selection
and masking. The property attributes of categories flagged with '@' are used
to control the behaviour of these special reference types.
|
| format: | @ |
| example: |
Sport
/Ball Sports
/@Soccer
/@Tennis
/Motor Sports
/@Formula 1
p: wheels = 4
/@Motor Racing
p: wheels = 2
/@Rally
p: wheels = 4
Car Sports +> /Sport # wheels >= 4
%
|