This form is used to add, save, or delete coordinates sets (also referred to here as frames) from a molecule. Usually these coordinates come from successive frames of a trajectory but, as shown in the tutorial A Quick Animation, can also be distinct conformations of the same structure.
When this form is used, it will affect only the molecule selected in the Selected Molecule chooser. There are three types of actions which can take place; read frames from or write frames to a file (in the CRD, DCD or PDB format) or delete frames from the current animation.