NAMD 3.1 (available in the Nightly Builds directory) now supports trajectory output for atom selections with different frequencies. This feature helps users save significant storage space by retaining high-frequency outputs only for regions of greatest interest and reduce the writing frequency for the rest of the system. The user can set different writing frequencies to different selections and compose trajectories as needed for analysis. The result is streamlined post-processing, easier segmented analysis by .dcd file, and faster data transfers.