What does it mean when it says '0' after a resistor value, for example 1k00 or 11k0?
It is (better, it is supposed to be if schematic's author has done a good job) an good indication of resistor tollerance.

If I  write 1k00 i.e. 1.00 kΩ I mean resistor should be between 995 Ω and 1004.999 Ω hence it must be a ±0.5% or better.  

Likewise if I had written 1k0 I'd have asked for a 950 Ω to 1049.999 Ω resitor i.e. ±5% or better one.

Basically one should not write meaningless digits, those shown in the number must be there because their are true.
So writing 1k00 5% is inconsistent and should be avoided while 1k 0.1% is ok for plain writing tolerance overrides missing digits.

Of course the same applies to any quantity.