Update changes the coordinates of a subset of atoms in a model. The user must supply either the transformed or original keywords and a PDB file named filename containing atom records with new atom coordinates. If USER FILE record(s) are present in the file, then the indicated models are updated; otherwise, the lowest-numbered model is updated. If HELIX or SHEET records are present in the file, they will take precedence over such records originally supplied with the model(s).
If the keyword is transformed, then the new coordinates are considered as having already been transformed by the current rotation and translation matrices. If the keyword is original, then the new coordinates are treated as untransformed coordinates and the current rotation and translation matrices are applied to the new coordinates before they are integrated with the rest of the model.