Is it allowed to modify system properties or add multiple values to system properties?

[uday_kumar_b]

Is it allowed to modify system properties or add multiple values to already existing system properties?
Here can the value have 'onhold' as well as an other value?

Do we need to create system property to have another value?

[Roshan Tiwari]

We should not modify the existing system properties which is already available either it OOB or custom until you don't aware about the working.