ELG: Default place filling
(Ilmen: As it seems this isn't clearly specified in the CLL, here is an explanation.)
As you know it, when one or several slots of the place structure of a selbri are left empty, they are implicitely filled with {zo'e}. However, some gismu don't seem to comply with this rule, namely those with a default value for one of their arguments.
Here is a couple of examples:
• fagri (fire) — x1 is a fire/flame in fuel x2 burning-in/reacting-with oxidizer x3 (default air/oxygen)
• nanca (year) — x1 is x2 years in duration (default is 1 year) by standard x3; (adjective:) x1 is annual
Proposed interpretation
• When a place with a default value isn't explicitly filled, it is implicitly filled with the default value.
• When a place without default value isn't explicitly filled, it is implicitly filled with zo'e.
• When a place with a default value is explicitly filled with zo'e or any other sumti, the default value does not apply.
Thus, in ti fagri, fagri3 is filled with the default value "air/oxygen", whereas in ti fagri fi zo'e, fagri3 is effectively unspecified.