A 'yes' value indicates that the language has dependent mood marking for when clauses. This is when a dedicated mood suffix marks a clause's role as the 'when' clause, but otherwise the clause is just like an ordinary finite clause. An example is Abkhaz, where all the distinctions of an ordinary finite clause are made, but they are made with special 'dependent mood' suffixes. For example, the independent marker for aorist is <i>yt'</i>, while the dependent marker for aorist is zero (Cristofaro 2008). 
<br><br><b>Reference</b><br>Cristofaro, Sonia. 2008. When Clauses.
In Haspelmath et al. (2008), chapter 126. Available online at <a href=â€http://wals.info/feature/126â€> http://wals.info/feature/126</a href>. 
