When using record files, the following data set access restrictions apply:

• Alias names for PDSE and PDS members are not supported by DFM. Only the true names can be used to access a file. Load libraries cannot be handled properly due to loss of link edit attributes.
• When accessing multivolume data sets, backward processing and direct positioning is not supported, some forms of insert processing to the end of the file are not supported, and retrieval and update requests do not work if they span physical volumes.

  See Application Programming Considerations for DDM record access restrictions for multivolume data sets.

• If a local z/OS® user updates a PDSE member that was created as a sequential file with associated DDM attributes, all the attributes will be lost. Because loss of attributes can cause data conversion and performance problems, local z/OS users should avoid updating PDSE members that are accessed by DFM.
• DFM cannot create or access SAM data sets or PDSE members with fixed record lengths greater than 32,760 or variable record lengths greater than 32,756. DFM cannot create or access VSAM data sets with record lengths greater than 32,760.