Keeping button pressed in X Plane 11

[tomrach]

Hello. What command using to set e.g. altitude or heading but using keyboard keeping button pressed?

Edit
Dataref Tool viewing altitude and heading only on datarefs list, not on command list: "sim/cockpit2/autopilot/altitude" and "sim/cockpit2/autopilot/heading"

[admin]

Don't understand what you're trying to achieve...