That is, from the left to the right:
. a colon.
-. mode for "src"; 000000 if creation or unmerged.
+. mode for "src"; 000000 if creation, or if "src" is from the index and is unmerged.
. a space.
-. mode for "dst"; 000000 if deletion or unmerged.
+. mode for "dst"; 000000 if deletion, or if "dst" is from the index and is unmerged.
. a space.
-. sha1 for "src"; 0\{40\} if creation or unmerged.
+. sha1 for "src"; 0\{40\} if creation, or if "src" is from the index and is unmerged.
. a space.
-. sha1 for "dst"; 0\{40\} if deletion, unmerged or "work tree out of sync with the index".
+. sha1 for "dst"; 0\{40\} if deletion, if "dst" is from the index and is unmerged, or if "dst" is from the work tree and is out of sync with the index.
. a space.
. status, followed by optional "score" number.
. a tab or a NUL when `-z` option is used.