字号 is read as じごう (jigou) and means nickname.
じごう
jigou
ろくじみょうごう
the six written characters of Buddha's name (used in prayer)
ろくじのみょうごう
だつじきごう
caret (symbol for omitted word)
きごうもじ
symbolic-character
こくさいふごうかもじしゅうごう
Universal Character Set
もじふごうでーたようそ
character-coded-data-element
じびき
dictionary
じすう
number of characters
じけい
character style
じびきがくもん
superficial learning
ばんごう
number
しんごう
traffic light