[hackers] [PATCH] nl.1: document pages

---
 nl.1 | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)
diff --git a/nl.1 b/nl.1
index 01ba9f5..052cdbe 100644
--- a/nl.1
+++ b/nl.1
_AT_@ -28,6 +28,23 @@ If no
 is given
 .Nm
 reads from stdin.
+.Pp
+.Nm
+treats the input text as a collection of logical pages divided into
+logical page sections.
+Each logical page consists of a header section, a body
+section and a footer section.
+Sections may be empty.
+The start of each section is indicated by a single delimiting line, one of:
+.Bl -column "\e:\e:\e: " "header " -offset indent
+.It Em "Line" Ta Em "Start of"
+.It \e:\e:\e:	header
+.It \e:\e:	body
+.It \e:	footer
+.El
+.Pp
+If the input text contains no delimiting line then all of the input text
+belongs to a single logical page body section.
 .Sh OPTIONS
 .Bl -tag -width Ds
 .It Fl p
-- 
2.26.2