To rename a member of a PDS, specify the member name in parenthesis after the PDS name. A DD statement is required to reference the disk volume containing the data set to be renamed. The older IBM utilities have rigid control statement formats. To continue a statement, you must code a trailing comma, type something in column 72, and continue the statement in column 16. Maintaining source statement libraries is a big job in the typical mainframe environment.
Most programmers are unaware of macros.
Most procedures are written and distributed by IBM and tailored to installation needs. Additional procedures are created by system programmers and senior application programmers at the installation. Unfortunately, an interactive text editor does not leave an audit trail of changes made to the library - and a person working interactively often makes mistakes. They tend to work fast and aren't as deliberate about the changes they are making. There are also times when the shear volume of changes makes use of an interactive text editor impractical.