CASE: how to add borders to a table?

In case you want to add borders to a table, to get a result like this for instance :

All you need to do, is to add a # at the end of the line (before the + though) that defines your table :

||     |  |  |  |  |  |  |  |  | 
|| {% t "Periode" %}    | 00 | 01 | 02 | 03 | 44 | 45 | 46 | 47 | 48 | 49 | 
|---|---------|---:|---:|---:|---:|---:|---:|---:|---:|---:|---:|---:#+