[sdiy] Oscillator sync schemes

[cheater cheater]

Hi guys,
I was wondering what different kinds of oscillator sync schemes there
are. There's of course hard sync. Are there multiple ways of doing
this? This is a cursory question - I've never heard of anything other
than 'reset the slave when the master resets'.

Then there's soft sync - it's quite undescribed. What are different
ways of doing 'soft sync'?

What are other ways of doing synchronization between two (or more) oscillators?

Cheers
Damian