Metric key equations for sidebearings on different masters

Hi - I apologize in advance if this is a dumb question:
I have 2 masters, and I use equations for the sidebearings (i.e. =H, =H/2…)
The sidebearings on one master (light) are automatically set on the other master (bold), and changing one affects the other. But I noticed that if I don’t use equations, they become ‘independent’.
The ‘linking’ Is it because of the equations then?

Thank you

Sorry - I just found out the answer – in the manual of course… (= vs. ==)