A ribonucleoprotein complex that contains an RNA of the box H/ACA type, a subtype of the small nucleolar RNA (snoRNA) family. RNA pseudouridylation (isomerization of uridine to pseudouridine) is the major, and most likely the ancestral, function of H/ACA RNPs, although some have evolved other functions. Pseudouridylation targets include both large and small ribosomal RNAs (rRNAs), and on U2 small nuclear RNA (U2 snRNA).