Sometimes a fixed Y-axis on a graph is not suitable for all hosts.

To make this more flexible, it would be nice if we could use a user macro to define the value of the fixed Y-axis scale so it can be defined on template and host level seperately.

This is also useful when you would like to change te scale 'on-the-fly' to have a better look at a baseline and ignoring a spike in the values. In this case te macro could be defined on the template level.
By temporarily setting the macro on the host level, the scale can be changed for futher inspection. Afterwards ou can clear te host macro and everything returns to normal.

The frontend should check if the macro contains a valid number, if not (or macro doesn't exist) use autoscaling instead?