A PDS Directory is a directory stored on a MVS host system.
A PDS Directory may be up to 44 characters in length, composed of the letters A-Z, the numerals 0-9, and the special characters period (.), dash (-), dollar sign ($), at sign (@), pound sign (#), and the underscore (_). The first and last characters of the name must not be a period (.) and two consecutive characters of the name must not both be periods.
In MVS parlance, a PDS Directory is known as a Partitioned Data Set (PDS) and the files it contains are referred to as Partitioned Data Set members.