fbm_instr(): tweak docs and formatting

Expand the commentary at the start of this function; add more blank lines
to separate chunks of code, and document what SVpbm_TAIL is for.

1 files changed, 1 insertions, 1 deletions

diff --git a/sv.h b/sv.h
index 57116d4fde..e1797de7d4 100644
--- a/sv.h
+++ b/sv.h
@@ -467,7 +467,7 @@ perform the upgrade if necessary.  See C<L</svtype>>.
 /* PVHV */
 #define SVphv_HASKFLAGS	0x80000000  /* keys have flag byte after hash */
 /* PVGV when SVpbm_VALID is true */
-#define SVpbm_TAIL	0x80000000
+#define SVpbm_TAIL	0x80000000  /* string has a fake "\n" appended */
 /* RV upwards. However, SVf_ROK and SVp_IOK are exclusive  */
 #define SVprv_WEAKREF   0x80000000  /* Weak reference */
 /* pad name vars only */