Flight Director Modes ALT, VS, Climb //Altitude Select Mode //Vertical Speed

Altitude Select Mode
Altitude Select Mode is comprised of Arm, Capture, and Track states. The
Arm state can be selected while other vertical modes are active. It monitors
aircraft closure rate towards the target altitude and determines the capture
point. Capture generates commands for a smooth, low g acquisition of the
target altitude. Track generates commands to maintain the target altitude

[@tonyty7354]

Perfect Explain relation b/w VS & ALT .