A when-construction describes two events that have some form of temporal, whether co-, sequential, or logical occurrence. In this type of construction, one of the two events is described in a phrase or clause that serves to answer the question When? This construction can appear as either (a) a verb or word derived from a verb or (b) a subordinate clause containing a finite verb (when-clause). This parameter considers whether the form in which a verb appears in a when-clause differs from that of an independent clause. If the two verb forms appear in the same form, the indirect verb form is termed balanced (Bal); if not, it is considered special or deranked (Drk). In the majority of languages, either a special form or base form must appear obligatorily, the latter being the significantly more frequent option. Other languages allow both possibilities, either obligatorily and in complementary distribution (based on grammatical or logical criteria), or optionally and interchangeably.
WhenVBal: The verb of a when-clause obligatorily appears in base form.
WhenVBalDiffV: The verb of a when-clause appears in either base form or a special form, depending on grammatical features of the verb, such as transitivity and aspect.
WhenVBalDiffT: The verb of a when-clause can appear in either base form or a special form, depending on its temporal relationship to the verb of the main clause.
WhenVDrk: The verb of a when-clause always appears in a single special form, regardless of both the features of the verb and the temporal relationship between it and the verb of the main clause.
WhenVDrkDiffV: The verb of a when-clause always appears in a special form, regardless of its temporal relationship to the verb of the main clause; however, the specific special form in which it appears (or can appear) depends on the features of the verb.
WhenVDrkDiffT: The verb of a when-clause always appears in a special form, regardless of the features of the verb; however, the specific special form in which it appears (or can appear) depends on its temporal relationship to the verb of the main clause.
+DrkSameSbj: The verb of a when-clause can only appear in a special form if its subject is coreferential with the subject of the main clause.
When a language displays more than one strategy, two values can be listed. The value +DrkSameSbj can only appear in conjunction with another value, with the exception of WhenVBal. If one strategy is dominant, a slash (/) can separate the two values, with the dominant value appearing first; if neither is dominant, they are listed with an ampersand (&) separating the two. The use of parentheses indicates that use of the strategy is not obligatory.
 If the difference between the reported clause and the independent verb form is that the reported clause has a special affix or clitic, and its removal would result in the form used in an independent clause, then the two verb forms are considered to be the same, since the affix functions as a conjunction marking the structure as a when-clause.
 Special or “demoted” verb forms are originally derived from a verb but now function as a different word class. Examples include gerunds, converbs, and participles. Special verb forms also include finite verbs that differ from the base form in their marking of person, case, cause, mood, or aspect or in their co-occurrence with adpositions (simple differences in tense do not apply!). These verb forms may also fulfill other functions in the language, in addition to their role in when-clauses.
 The commentary should specify whether use is obligatory or optional.
 This value also includes languages that do not grammatically mark the function served by when-clauses. In such languages, relations must be inferred logically or based on contextual cues.
 For example, the verb form may depend on whether the event in the when-clause happens before the event in the main clause, after it, or at the same time.
 “Appears” refers to obligatory use, whereas “can appear” refers to optional use. Although the parameter value applies equally to both types, it should be specified in the commentary whether use is obligatory or optional.