#### 3.4.1 Basic usage for `delta`

Although there are several valid command-line options for `delta`, they are not frequently used; the most common usage of delta is

    delta SCCS/s.umsp.c

and this command simply applies the changes to the file `umsp.c` to the SCCS file which tracks it. Though it is possible to specify the comment and MR-number for this change using command-line options, it’s more common to type them when prompted, unless `delta` is being driven by another program; either way, it’s unusual to specify options for `delta` on the command line.

Note that the filename you specify on the command line is that of the SCCS file, not the filename of the working file. The BSD wrapper program, sccs(1), will guess the correct filename for you, but this doesn’t happen unless you do actually invoke it (`sccs delta umsp.c` for example).