Each hunk begins with a line marked ‘====’. Three-way hunks have plain ‘====’ lines, and two-way hunks have ‘1’, ‘2’, or ‘3’ appended to specify which of the three input files differ in that hunk. The hunks contain copies of two or three sets of input lines each preceded by one or two commands identifying where the lines came from.
Normally, two spaces precede each copy of an input line to distinguish it from the commands. But with the --initial-tab (-T) option, diff3 uses a tab instead of two spaces; this lines up tabs correctly. See Tabs, for more information.
Commands take the following forms:
If the last line in a set of input lines is incomplete (see Incomplete Lines), it is distinguished on output from a full line by a following line that starts with ‘\’.