For sound and videorecordings, information about the trade name or recording system(s) (e.g., VHS), modulation frequency and number of lines of resolution may be included. Links to technical details relating to digital resources may also be recorded. For software, computer requirements may include computer manufacturer and model, operating system, or memory requirements; peripheral requirements may include number of tape drives, number of disk or drum units, number of terminals, or other peripheral devices, support software, or related equipment.