The double dot (seyame) in Classical Syriac.

The seyame sign-the double dot, was used in Classical Syriac to mark the plural.
For some written words there was no way to tell whether they denoted the singular or plural form like the word  ܡܠܟܐ for king or kings.

ܡ̈ܠܟܐ
/malke/
 'kings'

 vs.
ܡܠܟܐ
 /malka/
'king'

And

ܡܠܟܬܼܐ
/malktā/
Queen
vs
ܡ̈ܠܟܬܼܐ
/malkātā/
Queens