It's even worse in Ireland, where the word for 'Women' you will see on the toilet door is 'Mna', so easily converted by drunken dyslexia after a few too many pints of the black stuff into 'Man'.

While 'Men' is 'Fir' (as in Latin 'vir' -> virile, oddly, for a Celtic language), which may be abbreviated to 'F'.

Nightmare!

It's actually a problem in my line of work as a translator, because Spanish forms will often put 'Sexo: M', which could mean 'Sexo: Masculino' or 'Sexo: Mujer' (it's normally this, but not always - depends on the institution). If you haven't got the two checkbox options visible, or another person to compare against, to see if the opposite of 'M' is 'H' or 'F', you're lost.

The forename will often give it away. So long as you know the culture. People who don't speak Spanish might assume 'Amparo' is a man, as the name ends in an 'o', but it's 'María del Amparo'. Or than an Italian or Greek 'Andrea' is a woman, not an 'Andrew'.