A pulse wave is an artificial construct. It is all OFF (which is zero) for a portion of the wavecycle, and then all ON for the other portion of the wavecycle.
A square wave has a pulse width of 50%. Since 50% also means "half", this means the square wave is ON half the wavecycle, and OFF the other half. One half of the time it is fully on, the other half it's fully off. Easy enough. Just remember that we are still referencing 100%. So another way to look at it is, 50% of the time the wavecycle output is fully ON, while the other 50% of the time it is fully OFF.
So while it's tempting to think of a square wave as 50 0 50 0 50 0 50 0... just remember it's more like ON (for 50% of the wave's cycle), OFF (for 50% of the wave's cycle), ON (for 50%), OFF (for 50%).
A single square wave cycle is 50 on 50 off.
A single cycle of a pulse width wave with a pulse width of 10 has this pattern: 10% of the time ON, 90% of the time OFF. That's 10% of the time at full amplitude, the other 90% of the time at zero amplitude. Again, it's tempting to think of it a 10 0 10 0 10 0... but remember it's more like 10% of the time ON, 90% of the time OFF. 10 ON, 90 OFF, 10 ON, 90 OFF.
But it's cumbersome to write it all out as 10 ON, 90 OFF, 10 ON, 90 OFF. If we substitute 0 for the OFF portion, we will be mixing up our units, but it looks simpler: 10 0 10 0 10 0... It's implied that the OFF portion is the percentage left over from 100% after subtracting the ON portion: 10 0(that is, 0 or OFF for 90% of the cycle), 10 0(for 90% of the time), 10 0 (90%), 10 0(90), 10 0(90). The implied part is in parentheses.
So, for a waveform with pulse width of 30, we like to represent it as 30 0 30 0 30 0... but again, the implied portion is left out of the representation. In other words, it's really 30 0(70) 30 0(70) 30 0(70). We're always referencing 100%, but implying it.
So a pulse wave at 60 is represented as 60 0 60 0 60 0. (The implied portion is 40).