A node processes missing media in a clip based on the clip's settings (see Defining Missing Media Output). Most nodes that receive missing input from clips set to No Media will not process affected frames and display a warning. However, the BFX Output node automatically processes gaps in No Media clips as black frames.
There are nodes that process a No Media clip based on the type of input tab that is receiving the information. The Action, Paint, and Text nodes receive No Media clip information based on its source, and the current input and clip settings of the node's other inputs.