I found this post on the very interesting and gender-oriented blog The Society Pages, run by two Ph.D. in sociology, who are analysing the different sociological phenomena in the everyday living.
This time, the subject of analysis are the washroom signs.
‘Washroom signs are very telling of the way societies construct gender. They identify the male as the universal and the female as the variation. They express expectations of gender performance. And they conflate gender with sex’.
See the whole and deep typology and analysis of various washroom signs under this link.