Transcription factor (By similarity). Plays a role in embryogenesis and later development, perhaps acting redundantly with forkhead protein fkh-2 (PubMed:11044397). First expressed during embryogenesis in the AB lineage, as the lineage increases from 16 to 32 cells (PubMed:8162851, PubMed:9872954). Expression in the AB lineage diminishes around the 168 cell embryo stage and the expression pattern becomes symmetrical about the embryo's plane of bilateral symmetry (PubMed:8162851, PubMed:9872954). Also expressed in the lineage of the D founder cell initially in the 100 cell embryo (PubMed:8162851, PubMed:9872954). As embryonic elongation commences, expressed in Z1 and Z4 cells; this expression increases during the rest of embryogenesis and disappears shortly after hatching (PubMed:8162851). Expressed in the MS lineage, specifically in MSaaa and MSaap at the 51-cell stage (PubMed:9872954). RNAi-mediated knockdown by injection into adults has little or no phenotypic effect (PubMed:11044397). However, simultaneous knockdown of forkhead gene fkh-2 causes 12% of eggs produced by hermaphrodites to arrest development at late stages of embryogenesis and 81% arrest after hatching as L1 stage larvae (PubMed:11044397).