vav-reversive

Whenever you have:

1. an affix verb form,
2. with a vav-conjunction, and
3. it is the first word of the clause;

then this verb is reversed in much the same way as a vav-conversive “converts” a prefix form. It reverses the affix form of the verb from past tense, to future tense. Hence, KHW (8.1d) refer to these as “vav-reversives”. On occasion, a vav-reversive converts an affix verb to a modal idea. similar to a subjunctive in Greek or English video 'preterite' in this video refers to a prefix form of the verb with a vav-conversive. This video also uses the term 'vav-consecutive' to refer to both vav-conversives and vav-reversives.

More detail on the syntax of these forms is here.