Introduce the concept of nodes that are semantically transparent:

they are skipped when looking for previous or following high-level
macros.  Examples include roff(7) .ft, .ll, and .ta, mdoc(7) .Sm
and .Tg, and man(7) .DT and .PD.  Use this concept for a variety
of improved decisions in various validators and formatters.

While here,
* remove a few const qualifiers on struct arguments that caused trouble;
* get rid of some more Yoda notation in the vicinity;
* and apply some other stylistic improvements in the vicinity.

I found this class of issues while considering .Tg patches from kn@.

54 files changed, 835 insertions, 37 deletions

diff --git a/regress/man/HP/Makefile b/regress/man/HP/Makefile
index 1e33cfb4..945f5339 100644
--- a/regress/man/HP/Makefile
+++ b/regress/man/HP/Makefile
@@ -1,6 +1,6 @@
-# $OpenBSD: Makefile,v 1.3 2019/01/06 04:41:15 schwarze Exp $
+# $OpenBSD: Makefile,v 1.4 2020/02/27 01:25:58 schwarze Exp $
 
-REGRESS_TARGETS = break literal macrotag manyargs spacing
+REGRESS_TARGETS = break literal macrotag manyargs spacing vert
 HTML_TARGETS	= literal
 
 .include <bsd.regress.mk>
diff --git a/regress/man/HP/vert.in b/regress/man/HP/vert.in
new file mode 100644
index 00000000..b433c7e0
--- /dev/null
+++ b/regress/man/HP/vert.in
@@ -0,0 +1,14 @@
+.\" $OpenBSD: vert.in,v 1.1 2020/02/27 01:25:58 schwarze Exp $
+.TH HP-VERT 1 "February 19, 2020"
+.SH NAME
+HP-vert \- vertical spacing before hanged lists
+.SH DESCRIPTION
+.PD 2v
+.HP
+Each hanged paragraph gets a sufficient amount of text
+to wrap to the next line.
+.HP
+Each hanged paragraph gets a sufficient amount of text
+to wrap to the next line.
+.LP
+Normal text.
diff --git a/regress/man/HP/vert.out_ascii b/regress/man/HP/vert.out_ascii
new file mode 100644
index 00000000..30fa3dd4
--- /dev/null
+++ b/regress/man/HP/vert.out_ascii
@@ -0,0 +1,21 @@
+HP-VERT(1)                  General Commands Manual                 HP-VERT(1)
+
+
+
+NNAAMMEE
+       HP-vert - vertical spacing before hanged lists
+
+DDEESSCCRRIIPPTTIIOONN
+       Each hanged paragraph gets a sufficient amount of text to wrap to the
+              next line.
+
+
+       Each hanged paragraph gets a sufficient amount of text to wrap to the
+              next line.
+
+
+       Normal text.
+
+
+
+OpenBSD                        February 19, 2020                    HP-VERT(1)
diff --git a/regress/man/IP/Makefile b/regress/man/IP/Makefile
index a677b970..70094e5f 100644
--- a/regress/man/IP/Makefile
+++ b/regress/man/IP/Makefile
@@ -1,7 +1,8 @@
-# $OpenBSD: Makefile,v 1.9 2019/01/06 04:41:15 schwarze Exp $
+# $OpenBSD: Makefile,v 1.10 2020/02/27 01:25:58 schwarze Exp $
 
-REGRESS_TARGETS = empty literal longhead manyargs spacing width
+REGRESS_TARGETS = bullet empty literal longhead manyargs spacing vert width
+UTF8_TARGETS	= bullet
 LINT_TARGETS	= empty
-HTML_TARGETS	= literal
+HTML_TARGETS	= bullet literal
 
 .include <bsd.regress.mk>
diff --git a/regress/man/IP/bullet.in b/regress/man/IP/bullet.in
new file mode 100644
index 00000000..138a681b
--- /dev/null
+++ b/regress/man/IP/bullet.in
@@ -0,0 +1,22 @@
+.\" $OpenBSD: bullet.in,v 1.1 2020/02/27 01:25:58 schwarze Exp $
+.TH IP-BULLET 1 "February 20, 2020"
+.SH NAME
+IP-bullet \- bullet lists
+.SH DESCRIPTION
+BEGINTEST
+.IP * 3n
+one
+.IP *
+two
+.IP \(bu
+three
+.IP \(bu
+four
+.IP \-
+five
+.IP \-
+six
+.PP
+ENDTEST
+.br
+end of file
diff --git a/regress/man/IP/bullet.out_ascii b/regress/man/IP/bullet.out_ascii
new file mode 100644
index 00000000..a01f25c2
--- /dev/null
+++ b/regress/man/IP/bullet.out_ascii
@@ -0,0 +1,28 @@
+IP-BULLET(1)                General Commands Manual               IP-BULLET(1)
+
+
+
+NNAAMMEE
+       IP-bullet - bullet lists
+
+DDEESSCCRRIIPPTTIIOONN
+       BEGINTEST
+
+       *  one
+
+       *  two
+
+       +o  three
+
+       +o  four
+
+       -  five
+
+       -  six
+
+       ENDTEST
+       end of file
+
+
+
+OpenBSD                        February 20, 2020                  IP-BULLET(1)
diff --git a/regress/man/IP/bullet.out_html b/regress/man/IP/bullet.out_html
new file mode 100644
index 00000000..95c452b0
--- /dev/null
+++ b/regress/man/IP/bullet.out_html
@@ -0,0 +1,12 @@
+<ul class="Bl-bullet">
+  <li>one</li>
+  <li>two</li>
+</ul>
+<ul class="Bl-bullet">
+  <li>three</li>
+  <li>four</li>
+</ul>
+<ul class="Bl-dash">
+  <li>five</li>
+  <li>six</li>
+</ul>
diff --git a/regress/man/IP/bullet.out_utf8 b/regress/man/IP/bullet.out_utf8
new file mode 100644
index 00000000..fa021fd5
--- /dev/null
+++ b/regress/man/IP/bullet.out_utf8
@@ -0,0 +1,28 @@
+IP-BULLET(1)                General Commands Manual               IP-BULLET(1)
+
+
+
+NNAAMMEE
+       IP-bullet - bullet lists
+
+DDEESSCCRRIIPPTTIIOONN
+       BEGINTEST
+
+       *  one
+
+       *  two
+
+       •  three
+
+       •  four
+
+       -  five
+
+       -  six
+
+       ENDTEST
+       end of file
+
+
+
+OpenBSD                        February 20, 2020                  IP-BULLET(1)
diff --git a/regress/man/IP/vert.in b/regress/man/IP/vert.in
new file mode 100644
index 00000000..cc5e2038
--- /dev/null
+++ b/regress/man/IP/vert.in
@@ -0,0 +1,10 @@
+.\" $OpenBSD: vert.in,v 1.1 2020/02/27 01:25:58 schwarze Exp $
+.TH IP-VERT 1 "February 19, 2020"
+.SH NAME
+IP-vert \- vertical spacing before indented paragraphs
+.SH DESCRIPTION
+.PD 2v
+.IP tag
+text
+.IP tag
+text
diff --git a/regress/man/IP/vert.out_ascii b/regress/man/IP/vert.out_ascii
new file mode 100644
index 00000000..428733be
--- /dev/null
+++ b/regress/man/IP/vert.out_ascii
@@ -0,0 +1,16 @@
+IP-VERT(1)                  General Commands Manual                 IP-VERT(1)
+
+
+
+NNAAMMEE
+       IP-vert - vertical spacing before indented paragraphs
+
+DDEESSCCRRIIPPTTIIOONN
+       tag    text
+
+
+       tag    text
+
+
+
+OpenBSD                        February 19, 2020                    IP-VERT(1)
diff --git a/regress/man/PP/Makefile b/regress/man/PP/Makefile
index 7655d294..a9eb9760 100644
--- a/regress/man/PP/Makefile
+++ b/regress/man/PP/Makefile
@@ -1,6 +1,6 @@
-# $OpenBSD: Makefile,v 1.4 2014/07/04 16:11:41 schwarze Exp $
+# $OpenBSD: Makefile,v 1.5 2020/02/27 01:25:58 schwarze Exp $
 
-REGRESS_TARGETS	= args empty
+REGRESS_TARGETS	= args empty vert
 LINT_TARGETS	= args empty
 
 .include <bsd.regress.mk>
diff --git a/regress/man/PP/vert.in b/regress/man/PP/vert.in
new file mode 100644
index 00000000..e15148c8
--- /dev/null
+++ b/regress/man/PP/vert.in
@@ -0,0 +1,10 @@
+.\" $OpenBSD: vert.in,v 1.1 2020/02/27 01:25:58 schwarze Exp $
+.TH PP-VERT 1 "February 19, 2020"
+.SH NAME
+PP-vert \- vertical spacing before an ordinary paragraph
+.SH DESCRIPTION
+.PD 2v
+.PP
+first paragraph
+.PP
+second paragraph
diff --git a/regress/man/PP/vert.out_ascii b/regress/man/PP/vert.out_ascii
new file mode 100644
index 00000000..ac53e071
--- /dev/null
+++ b/regress/man/PP/vert.out_ascii
@@ -0,0 +1,16 @@
+PP-VERT(1)                  General Commands Manual                 PP-VERT(1)
+
+
+
+NNAAMMEE
+       PP-vert - vertical spacing before an ordinary paragraph
+
+DDEESSCCRRIIPPTTIIOONN
+       first paragraph
+
+
+       second paragraph
+
+
+
+OpenBSD                        February 19, 2020                    PP-VERT(1)
diff --git a/regress/man/SH/Makefile b/regress/man/SH/Makefile
index 55133efe..f42a85b2 100644
--- a/regress/man/SH/Makefile
+++ b/regress/man/SH/Makefile
@@ -1,6 +1,6 @@
-# $OpenBSD: Makefile,v 1.6 2019/01/06 04:41:15 schwarze Exp $
+# $OpenBSD: Makefile,v 1.7 2020/02/27 01:25:58 schwarze Exp $
 
-REGRESS_TARGETS	= broken broken_eline empty_before longarg noarg paragraph
+REGRESS_TARGETS	= broken broken_eline empty_before longarg noarg paragraph vert
 LINT_TARGETS	= broken broken_eline empty_before noarg
 HTML_TARGETS	= paragraph
 
diff --git a/regress/man/SH/vert.in b/regress/man/SH/vert.in
new file mode 100644
index 00000000..e4154782
--- /dev/null
+++ b/regress/man/SH/vert.in
@@ -0,0 +1,10 @@
+.\" $OpenBSD: vert.in,v 1.1 2020/02/27 01:25:58 schwarze Exp $
+.TH SH-VERT 1 "February 20, 2020"
+.SH NAME
+SH-vert \- vertical spacing of sections
+.SH DESCRIPTION
+.PD 2v
+.SH EXAMPLES
+.PD 1v
+.PP
+text
diff --git a/regress/man/SH/vert.out_ascii b/regress/man/SH/vert.out_ascii
new file mode 100644
index 00000000..f8afd7e0
--- /dev/null
+++ b/regress/man/SH/vert.out_ascii
@@ -0,0 +1,14 @@
+SH-VERT(1)                  General Commands Manual                 SH-VERT(1)
+
+
+
+NNAAMMEE
+       SH-vert - vertical spacing of sections
+
+DDEESSCCRRIIPPTTIIOONN
+EEXXAAMMPPLLEESS
+       text
+
+
+
+OpenBSD                        February 20, 2020                    SH-VERT(1)
diff --git a/regress/man/SS/Makefile b/regress/man/SS/Makefile
index 0ae0fbc5..edbe4c2c 100644
--- a/regress/man/SS/Makefile
+++ b/regress/man/SS/Makefile
@@ -1,6 +1,6 @@
-# $OpenBSD: Makefile,v 1.4 2019/01/06 04:41:15 schwarze Exp $
+# $OpenBSD: Makefile,v 1.5 2020/02/27 01:25:58 schwarze Exp $
 
-REGRESS_TARGETS	= broken broken_eline longarg noarg paragraph
+REGRESS_TARGETS	= broken broken_eline longarg noarg paragraph vert
 LINT_TARGETS	= broken broken_eline noarg
 HTML_TARGETS	= paragraph
 
diff --git a/regress/man/SS/vert.in b/regress/man/SS/vert.in
new file mode 100644
index 00000000..8beb98a6
--- /dev/null
+++ b/regress/man/SS/vert.in
@@ -0,0 +1,12 @@
+.\" $OpenBSD: vert.in,v 1.1 2020/02/27 01:25:58 schwarze Exp $
+.TH SS-VERT 1 "February 19, 2020"
+.SH NAME
+SS-vert \- vertical spacing of subsections
+.SH DESCRIPTION
+.PD 2v
+.SS First subsection
+.PD 1v
+.SS Second subsection
+first paragraph
+.PP
+second paragraph
diff --git a/regress/man/SS/vert.out_ascii b/regress/man/SS/vert.out_ascii
new file mode 100644
index 00000000..9b5dc152
--- /dev/null
+++ b/regress/man/SS/vert.out_ascii
@@ -0,0 +1,17 @@
+SS-VERT(1)                  General Commands Manual                 SS-VERT(1)
+
+
+
+NNAAMMEE
+       SS-vert - vertical spacing of subsections
+
+DDEESSCCRRIIPPTTIIOONN
+   FFiirrsstt ssuubbsseeccttiioonn
+   SSeeccoonndd ssuubbsseeccttiioonn
+       first paragraph
+
+       second paragraph
+
+
+
+OpenBSD                        February 19, 2020                    SS-VERT(1)
diff --git a/regress/man/TP/Makefile b/regress/man/TP/Makefile
index 2fc1074f..ca2475b0 100644
--- a/regress/man/TP/Makefile
+++ b/regress/man/TP/Makefile
@@ -1,9 +1,9 @@
-# $OpenBSD: Makefile,v 1.15 2019/01/06 04:41:15 schwarze Exp $
+# $OpenBSD: Makefile,v 1.16 2020/02/27 01:25:58 schwarze Exp $
 
 REGRESS_TARGETS	 = badarg broken double eof fill indent literal longhead
-REGRESS_TARGETS	+= macrotag manyargs sameline spacing width
+REGRESS_TARGETS	+= macrotag manyargs sameline spacing vert width
 LINT_TARGETS	 = broken double eof
-HTML_TARGETS	 = literal
+HTML_TARGETS	 = literal vert
 
 # groff-1.22.3 defects:
 # - If .TP precedes .RE, the latter does not properly reset indentation.
diff --git a/regress/man/TP/vert.in b/regress/man/TP/vert.in
new file mode 100644
index 00000000..086976df
--- /dev/null
+++ b/regress/man/TP/vert.in
@@ -0,0 +1,17 @@
+.\" $OpenBSD: vert.in,v 1.1 2020/02/27 01:25:58 schwarze Exp $
+.TH TP-VERT 1 "February 19, 2020"
+.SH NAME
+TP-vert \- vertical spacing before tagged paragraphs
+BEGINTEST
+.SH DESCRIPTION
+.PD 2v
+.TP
+tag
+text
+.TP
+tag
+text
+.PP
+ENDTEST
+.br
+end of file
diff --git a/regress/man/TP/vert.out_ascii b/regress/man/TP/vert.out_ascii
new file mode 100644
index 00000000..32b26ca9
--- /dev/null
+++ b/regress/man/TP/vert.out_ascii
@@ -0,0 +1,20 @@
+TP-VERT(1)                  General Commands Manual                 TP-VERT(1)
+
+
+
+NNAAMMEE
+       TP-vert - vertical spacing before tagged paragraphs BEGINTEST
+
+DDEESSCCRRIIPPTTIIOONN
+       tag    text
+
+
+       tag    text
+
+
+       ENDTEST
+       end of file
+
+
+
+OpenBSD                        February 19, 2020                    TP-VERT(1)
diff --git a/regress/man/TP/vert.out_html b/regress/man/TP/vert.out_html
new file mode 100644
index 00000000..7301819f
--- /dev/null
+++ b/regress/man/TP/vert.out_html
@@ -0,0 +1,9 @@
+</section>
+<section class="Sh">
+<h1 class="Sh" id="DESCRIPTION"><a class="permalink" href="#DESCRIPTION">DESCRIPTION</a></h1>
+<dl class="Bl-tag">
+  <dt>tag</dt>
+  <dd>text</dd>
+  <dt>tag</dt>
+  <dd>text</dd>
+</dl>
diff --git a/regress/mdoc/Bd/spacing.in b/regress/mdoc/Bd/spacing.in
index b29f6da4..dfe86387 100644
--- a/regress/mdoc/Bd/spacing.in
+++ b/regress/mdoc/Bd/spacing.in
@@ -1,5 +1,5 @@
-.\" $OpenBSD: spacing.in,v 1.3 2017/07/04 14:53:24 schwarze Exp $
-.Dd $Mdocdate: July 4 2017 $
+.\" $OpenBSD: spacing.in,v 1.4 2020/02/27 01:25:58 schwarze Exp $
+.Dd $Mdocdate: February 27 2020 $
 .Dt BD-SPACING 1
 .Os
 .Sh NAME
@@ -15,3 +15,9 @@ text between displays
 compact display block
 .Ed
 following text
+.Sh EXAMPLES
+.Tg word
+.Bd -literal -offset indent
+text
+.Ed
+end of file
diff --git a/regress/mdoc/Bd/spacing.out_ascii b/regress/mdoc/Bd/spacing.out_ascii
index 8efa8b30..e965647c 100644
--- a/regress/mdoc/Bd/spacing.out_ascii
+++ b/regress/mdoc/Bd/spacing.out_ascii
@@ -11,4 +11,8 @@ DDEESSCCRRIIPPTTIIOONN
            compact display block
      following text
 
-OpenBSD                          July 4, 2017                          OpenBSD
+EEXXAAMMPPLLEESS
+           text
+     end of file
+
+OpenBSD                        February 27, 2020                       OpenBSD
diff --git a/regress/mdoc/Bd/spacing.out_markdown b/regress/mdoc/Bd/spacing.out_markdown
index 766dda3b..a03c20ef 100644
--- a/regress/mdoc/Bd/spacing.out_markdown
+++ b/regress/mdoc/Bd/spacing.out_markdown
@@ -16,4 +16,10 @@ text between displays
 
 following text
 
-OpenBSD - July 4, 2017
+# EXAMPLES
+
+	text
+
+end of file
+
+OpenBSD - February 27, 2020
diff --git a/regress/mdoc/Bl/Makefile b/regress/mdoc/Bl/Makefile
index 8fde5d9e..519c4055 100644
--- a/regress/mdoc/Bl/Makefile
+++ b/regress/mdoc/Bl/Makefile
@@ -1,8 +1,8 @@
-# $OpenBSD: Makefile,v 1.40 2018/12/21 16:58:49 schwarze Exp $
+# $OpenBSD: Makefile,v 1.41 2020/02/27 01:25:58 schwarze Exp $
 
 REGRESS_TARGETS  = item inset diag ohang bullet dash enum hang tag
 REGRESS_TARGETS += column column_nogroff colNoIt
-REGRESS_TARGETS += esc extend nested offset secstart
+REGRESS_TARGETS += esc extend nested offset secstart vert
 
 REGRESS_TARGETS += notype multitype badargs
 REGRESS_TARGETS += empty noIt emptyhead emptytag emptyitem multitag
diff --git a/regress/mdoc/Bl/noIt.out_lint b/regress/mdoc/Bl/noIt.out_lint
index 03a89cc5..7c6803f3 100644
--- a/regress/mdoc/Bl/noIt.out_lint
+++ b/regress/mdoc/Bl/noIt.out_lint
@@ -6,3 +6,4 @@ mandoc: noIt.in:18:2: WARNING: moving content out of list: Em
 mandoc: noIt.in:18:10: WARNING: moving content out of list: Sy
 mandoc: noIt.in:18:19: WARNING: moving content out of list: Em
 mandoc: noIt.in:24:1: WARNING: moving content out of list: text
+mandoc: noIt.in:23:2: WARNING: empty block: Bl
diff --git a/regress/mdoc/Bl/vert.in b/regress/mdoc/Bl/vert.in
new file mode 100644
index 00000000..b17b897c
--- /dev/null
+++ b/regress/mdoc/Bl/vert.in
@@ -0,0 +1,15 @@
+.\" $OpenBSD: vert.in,v 1.1 2020/02/27 01:25:58 schwarze Exp $
+.Dd $Mdocdate: February 27 2020 $
+.Dt BL-VERT 1
+.Os
+.Sh NAME
+.Nm Bl-vert
+.Nd vertical spacing before lists
+.Sh DESCRIPTION
+.Bl -tag -width 7n
+.Sm off
+.It Fl o Ar file
+.Sm on
+text
+.El
+end of file
diff --git a/regress/mdoc/Bl/vert.out_ascii b/regress/mdoc/Bl/vert.out_ascii
new file mode 100644
index 00000000..24a2c565
--- /dev/null
+++ b/regress/mdoc/Bl/vert.out_ascii
@@ -0,0 +1,10 @@
+BL-VERT(1)                  General Commands Manual                 BL-VERT(1)
+
+NNAAMMEE
+     BBll--vveerrtt - vertical spacing before lists
+
+DDEESSCCRRIIPPTTIIOONN
+     --oo_f_i_l_e   text
+     end of file
+
+OpenBSD                        February 27, 2020                       OpenBSD
diff --git a/regress/mdoc/Bl/vert.out_markdown b/regress/mdoc/Bl/vert.out_markdown
new file mode 100644
index 00000000..ed741b40
--- /dev/null
+++ b/regress/mdoc/Bl/vert.out_markdown
@@ -0,0 +1,15 @@
+BL-VERT(1) - General Commands Manual
+
+# NAME
+
+**Bl-vert** - vertical spacing before lists
+
+# DESCRIPTION
+
+**-o**&zwnj;*file*
+
+> text
+
+end of file
+
+OpenBSD - February 27, 2020
diff --git a/regress/mdoc/Fl/Makefile b/regress/mdoc/Fl/Makefile
index f2b2a9aa..e4e4a6bc 100644
--- a/regress/mdoc/Fl/Makefile
+++ b/regress/mdoc/Fl/Makefile
@@ -1,6 +1,6 @@
-# $OpenBSD: Makefile,v 1.8 2014/08/21 12:56:24 schwarze Exp $
+# $OpenBSD: Makefile,v 1.13 2020/02/27 01:25:58 schwarze Exp $
 
-REGRESS_TARGETS = noarg multiarg parsed punct font
+REGRESS_TARGETS = font multiarg noarg parsed punct spacing
 LINT_TARGETS	= punct
 
 .include <bsd.regress.mk>
diff --git a/regress/mdoc/Fl/spacing.in b/regress/mdoc/Fl/spacing.in
new file mode 100644
index 00000000..6b59478f
--- /dev/null
+++ b/regress/mdoc/Fl/spacing.in
@@ -0,0 +1,42 @@
+.\" $OpenBSD: spacing.in,v 1.1 2020/02/27 01:25:58 schwarze Exp $
+.Dd $Mdocdate: February 27 2020 $
+.Dt FL-SPACING 1
+.Os
+.Sh NAME
+.Nm Fl-spacing
+.Nd horizontal spacing after flag macros
+.Sh DESCRIPTION
+with argument:
+.Fl a
+.Pp
+no next node:
+.Xo Fl Xc suffix
+.Pp
+transparent next node only:
+.Xo Fl
+.Tg transparent1
+.Xc suffix
+.Pp
+following text:
+.Fl
+text
+.Pp
+text after transparent node on the same line:
+.Fl Es < >
+text
+.Pp
+following macro on the same line:
+.Fl Em word
+.Pp
+following macro on the next line:
+.Fl
+.Em word
+.Pp
+following macro on the next line after transparent node on the same line:
+.Fl Es < >
+.Em word
+.Pp
+following macro after transparent node on the next line:
+.Fl
+.Tg transparent3
+.Em word
diff --git a/regress/mdoc/Fl/spacing.out_ascii b/regress/mdoc/Fl/spacing.out_ascii
new file mode 100644
index 00000000..c96c3923
--- /dev/null
+++ b/regress/mdoc/Fl/spacing.out_ascii
@@ -0,0 +1,26 @@
+FL-SPACING(1)               General Commands Manual              FL-SPACING(1)
+
+NNAAMMEE
+     FFll--ssppaacciinngg - horizontal spacing after flag macros
+
+DDEESSCCRRIIPPTTIIOONN
+     with argument: --aa
+
+     no next node: -- suffix
+
+     transparent next node only: -- suffix
+
+     following text: -- text
+
+     text after transparent node on the same line: -- text
+
+     following macro on the same line: --_w_o_r_d
+
+     following macro on the next line: -- _w_o_r_d
+
+     following macro on the next line after transparent node on the same line:
+     -- _w_o_r_d
+
+     following macro after transparent node on the next line: -- _w_o_r_d
+
+OpenBSD                        February 27, 2020                       OpenBSD
diff --git a/regress/mdoc/Fl/spacing.out_markdown b/regress/mdoc/Fl/spacing.out_markdown
new file mode 100644
index 00000000..a46a44e3
--- /dev/null
+++ b/regress/mdoc/Fl/spacing.out_markdown
@@ -0,0 +1,42 @@
+FL-SPACING(1) - General Commands Manual
+
+# NAME
+
+**Fl-spacing** - horizontal spacing after flag macros
+
+# DESCRIPTION
+
+with argument:
+**-a**
+
+no next node:
+**-** suffix
+
+transparent next node only:
+**-**
+suffix
+
+following text:
+**-**
+text
+
+text after transparent node on the same line:
+**-**
+text
+
+following macro on the same line:
+**-**&zwnj;*word*
+
+following macro on the next line:
+**-**
+*word*
+
+following macro on the next line after transparent node on the same line:
+**-**
+*word*
+
+following macro after transparent node on the next line:
+**-**
+*word*
+
+OpenBSD - February 27, 2020
diff --git a/regress/mdoc/Fo/Makefile b/regress/mdoc/Fo/Makefile
index 09941a52..7770e9a1 100644
--- a/regress/mdoc/Fo/Makefile
+++ b/regress/mdoc/Fo/Makefile
@@ -1,7 +1,7 @@
-# $OpenBSD: Makefile,v 1.13 2015/02/16 11:39:34 schwarze Exp $
+# $OpenBSD: Makefile,v 1.17 2020/02/27 01:25:58 schwarze Exp $
 
 REGRESS_TARGETS	 = basic break eos font noarg nohead
-REGRESS_TARGETS += obsolete punct section warn
+REGRESS_TARGETS += obsolete punct section transp warn
 LINT_TARGETS	 = noarg nohead obsolete punct warn
 
 # groff-1.22.3 defects:
diff --git a/regress/mdoc/Fo/transp.in b/regress/mdoc/Fo/transp.in
new file mode 100644
index 00000000..3ca83287
--- /dev/null
+++ b/regress/mdoc/Fo/transp.in
@@ -0,0 +1,23 @@
+.\" $OpenBSD: transp.in,v 1.1 2020/02/27 01:25:58 schwarze Exp $
+.Dd $Mdocdate: February 27 2020 $
+.Dt FO-TRANSP 1
+.Os
+.Sh NAME
+.Nm Fo-transp
+.Nd transparent nodes among function argument macros
+.Sh SYNOPSIS
+.Ft type
+.Fo func
+.Fa one
+.Tg one
+.Fa two
+.Tg two
+.Fc
+.Sh DESCRIPTION
+.Ft type
+.Fo func
+.Fa one
+.Tg one
+.Fa two
+.Tg two
+.Fc
diff --git a/regress/mdoc/Fo/transp.out_ascii b/regress/mdoc/Fo/transp.out_ascii
new file mode 100644
index 00000000..fb0c37fc
--- /dev/null
+++ b/regress/mdoc/Fo/transp.out_ascii
@@ -0,0 +1,13 @@
+FO-TRANSP(1)                General Commands Manual               FO-TRANSP(1)
+
+NNAAMMEE
+     FFoo--ttrraannsspp - transparent nodes among function argument macros
+
+SSYYNNOOPPSSIISS
+     _t_y_p_e
+     ffuunncc(_o_n_e, _t_w_o);
+
+DDEESSCCRRIIPPTTIIOONN
+     _t_y_p_e ffuunncc(_o_n_e, _t_w_o)
+
+OpenBSD                        February 27, 2020                       OpenBSD
diff --git a/regress/mdoc/Fo/transp.out_markdown b/regress/mdoc/Fo/transp.out_markdown
new file mode 100644
index 00000000..237d7819
--- /dev/null
+++ b/regress/mdoc/Fo/transp.out_markdown
@@ -0,0 +1,19 @@
+FO-TRANSP(1) - General Commands Manual
+
+# NAME
+
+**Fo-transp** - transparent nodes among function argument macros
+
+# SYNOPSIS
+
+*type*  
+**func**(*one*,
+*two*);
+
+# DESCRIPTION
+
+*type*
+**func**(*one*,
+*two*)
+
+OpenBSD - February 27, 2020
diff --git a/regress/mdoc/Rs/Makefile b/regress/mdoc/Rs/Makefile
index 2881b874..e6e3e1bc 100644
--- a/regress/mdoc/Rs/Makefile
+++ b/regress/mdoc/Rs/Makefile
@@ -1,6 +1,6 @@
-# $OpenBSD: Makefile,v 1.11 2019/01/07 06:51:37 schwarze Exp $
+# $OpenBSD: Makefile,v 1.12 2020/02/27 01:25:58 schwarze Exp $
 
-REGRESS_TARGETS	 = allch args break empty paragraph three_authors
+REGRESS_TARGETS	 = allch args break empty paragraph three_authors transp
 UTF8_TARGETS	 = allch break empty three_authors
 LINT_TARGETS	 = allch args empty
 HTML_TARGETS	 = paragraph
diff --git a/regress/mdoc/Rs/transp.in b/regress/mdoc/Rs/transp.in
new file mode 100644
index 00000000..7e906d00
--- /dev/null
+++ b/regress/mdoc/Rs/transp.in
@@ -0,0 +1,36 @@
+.\" $OpenBSD: transp.in,v 1.1 2020/02/27 01:25:58 schwarze Exp $
+.Dd $Mdocdate: February 27 2020 $
+.Dt RS-TRANSPARENT 1
+.Os
+.Sh NAME
+.Nm Rs-transparent
+.Nd transparent nodes in reference blocks
+.Sh SEE ALSO
+.Tg transparent
+.Rs
+.%T title
+.%A first after title
+.%A last
+.Re
+.Rs
+.%A first
+.%A middle
+.%A last before title
+.%T title
+.Re
+.Rs
+.%T title
+.Tg transparent
+.%A first after title and transparent
+.%A middle before transparent
+.Tg transparent
+.%A last before transparent
+.Tg transparent
+.Re
+.Rs
+.Tg transparent
+.%A first after transparent
+.%A last before transparent and title
+.Tg transparent
+.%T title
+.Re
diff --git a/regress/mdoc/Rs/transp.out_ascii b/regress/mdoc/Rs/transp.out_ascii
new file mode 100644
index 00000000..cc217ed5
--- /dev/null
+++ b/regress/mdoc/Rs/transp.out_ascii
@@ -0,0 +1,16 @@
+RS-TRANSPARENT(1)           General Commands Manual          RS-TRANSPARENT(1)
+
+NNAAMMEE
+     RRss--ttrraannssppaarreenntt - transparent nodes in reference blocks
+
+SSEEEE AALLSSOO
+     first after title and last, _t_i_t_l_e.
+
+     first, middle, and last before title, _t_i_t_l_e.
+
+     first after title and transparent, middle before transparent, and last
+     before transparent, _t_i_t_l_e.
+
+     first after transparent and last before transparent and title, _t_i_t_l_e.
+
+OpenBSD                        February 27, 2020                       OpenBSD
diff --git a/regress/mdoc/Rs/transp.out_markdown b/regress/mdoc/Rs/transp.out_markdown
new file mode 100644
index 00000000..a9896335
--- /dev/null
+++ b/regress/mdoc/Rs/transp.out_markdown
@@ -0,0 +1,27 @@
+RS-TRANSPARENT(1) - General Commands Manual
+
+# NAME
+
+**Rs-transparent** - transparent nodes in reference blocks
+
+# SEE ALSO
+
+first after title,
+last,
+*title*.
+
+first,
+middle, and
+last before title,
+*title*.
+
+first after title and transparent,
+middle before transparent, and
+last before transparent,
+*title*.
+
+first after transparent,
+last before transparent and title,
+*title*.
+
+OpenBSD - February 27, 2020
diff --git a/regress/mdoc/Sh/Makefile b/regress/mdoc/Sh/Makefile
index 1c20f13f..213664ec 100644
--- a/regress/mdoc/Sh/Makefile
+++ b/regress/mdoc/Sh/Makefile
@@ -1,7 +1,8 @@
-# $OpenBSD: Makefile,v 1.11 2019/01/07 06:51:37 schwarze Exp $
+# $OpenBSD: Makefile,v 1.12 2020/02/27 01:25:58 schwarze Exp $
 
 REGRESS_TARGETS	 = badNAME before empty emptyNAME first nohead order
-REGRESS_TARGETS	+= orderNAME paragraph parbefore parborder punctNAME subbefore
+REGRESS_TARGETS	+= orderNAME paragraph parbefore parborder punctNAME
+REGRESS_TARGETS	+= subbefore transp
 LINT_TARGETS	 = badNAME before empty emptyNAME first nohead order
 LINT_TARGETS	+= orderNAME parbefore parborder punctNAME subbefore
 HTML_TARGETS	 = paragraph
diff --git a/regress/mdoc/Sh/transp.in b/regress/mdoc/Sh/transp.in
new file mode 100644
index 00000000..843c4931
--- /dev/null
+++ b/regress/mdoc/Sh/transp.in
@@ -0,0 +1,11 @@
+.\" $OpenBSD: transp.in,v 1.1 2020/02/27 01:25:58 schwarze Exp $
+.Dd $Mdocdate: February 27 2020 $
+.Dt SH-TRANSP 1
+.Os
+.Sh NAME
+.Nm Sh-transp
+.Nd interaction of sections with transparent nodes
+.Sh DESCRIPTION
+.Tg transparent
+.Ss Subsection
+text
diff --git a/regress/mdoc/Sh/transp.out_ascii b/regress/mdoc/Sh/transp.out_ascii
new file mode 100644
index 00000000..e30d327f
--- /dev/null
+++ b/regress/mdoc/Sh/transp.out_ascii
@@ -0,0 +1,10 @@
+SH-TRANSP(1)                General Commands Manual               SH-TRANSP(1)
+
+NNAAMMEE
+     SShh--ttrraannsspp - interaction of sections with transparent nodes
+
+DDEESSCCRRIIPPTTIIOONN
+   SSuubbsseeccttiioonn
+     text
+
+OpenBSD                        February 27, 2020                       OpenBSD
diff --git a/regress/mdoc/Sh/transp.out_markdown b/regress/mdoc/Sh/transp.out_markdown
new file mode 100644
index 00000000..f395ed50
--- /dev/null
+++ b/regress/mdoc/Sh/transp.out_markdown
@@ -0,0 +1,13 @@
+SH-TRANSP(1) - General Commands Manual
+
+# NAME
+
+**Sh-transp** - interaction of sections with transparent nodes
+
+# DESCRIPTION
+
+## Subsection
+
+text
+
+OpenBSD - February 27, 2020
diff --git a/regress/mdoc/Sm/badarg.out_markdown b/regress/mdoc/Sm/badarg.out_markdown
index 903b7f81..92fc66b1 100644
--- a/regress/mdoc/Sm/badarg.out_markdown
+++ b/regress/mdoc/Sm/badarg.out_markdown
@@ -8,7 +8,6 @@ SM-BADARG(1) - General Commands Manual
 
 **-f** *on*
 **-f**&zwnj;*off* bad
-**-f** *bad* (on)
-bad**-f**&zwnj;*bad*(off)
+**-f** *bad* (on) bad**-f**&zwnj;*bad*(off)
 
 OpenBSD-July 4, 2017
diff --git a/regress/mdoc/Sm/twoarg.out_markdown b/regress/mdoc/Sm/twoarg.out_markdown
index 5b64aa6e..ce46afb1 100644
--- a/regress/mdoc/Sm/twoarg.out_markdown
+++ b/regress/mdoc/Sm/twoarg.out_markdown
@@ -8,12 +8,10 @@ SM-TWOARG(1) - General Commands Manual
 
 **default**:
 **-f** *on*  
-**off two**:
-two**-f**&zwnj;*off*  
+**off two**: two**-f**&zwnj;*off*  
 **badtwo**: bad two
 **-f** *off*  
-**on two**:
-two
+**on two**: two
 **-f** *on*
 
 OpenBSD - July 4, 2017
diff --git a/regress/mdoc/blank/Makefile b/regress/mdoc/blank/Makefile
index 7dfd0287..8b61f902 100644
--- a/regress/mdoc/blank/Makefile
+++ b/regress/mdoc/blank/Makefile
@@ -1,7 +1,7 @@
-# $OpenBSD: Makefile,v 1.5 2014/07/06 19:08:57 schwarze Exp $
+# $OpenBSD: Makefile,v 1.8 2020/02/27 01:25:59 schwarze Exp $
 
-REGRESS_TARGETS = line comment list
-LINT_TARGETS	= line comment list
+REGRESS_TARGETS = line comment list transp
+LINT_TARGETS	= line comment list transp
 
 SKIP_TMAN = list
 SKIP_MARKDOWN ?= line
diff --git a/regress/mdoc/blank/transp.in b/regress/mdoc/blank/transp.in
new file mode 100644
index 00000000..6dcb2251
--- /dev/null
+++ b/regress/mdoc/blank/transp.in
@@ -0,0 +1,77 @@
+.\" $OpenBSD: transp.in,v 1.1 2020/02/27 01:25:59 schwarze Exp $
+.Dd $Mdocdate: February 27 2020 $
+.Dt BLANK-TRANSP 1
+.Os
+.Sh NAME
+.Nm blank-transp
+.Nd transparent nodes between line breaks
+.Sh DESCRIPTION
+Double br:
+.br
+.Tg brbr
+.br
+br Pp:
+.br
+.Tg brPp
+.Pp
+Pp br:
+.Pp
+.Tg Ppbr
+.br
+Double Pp:
+.Pp
+.Tg PpPp
+.Pp
+br sp:
+.br
+.Tg brsp
+.sp
+sp br:
+.sp
+.Tg spbr
+.br
+Pp sp:
+.Pp
+.Tg Ppsp
+.sp
+Pp sp 2v:
+.Pp
+.Tg Ppsp2v
+.sp 2v
+sp Pp:
+.sp
+.Tg spPp
+.Pp
+Double sp:
+.sp
+.Tg spsp
+.sp
+br blank:
+.br
+.Tg brbl
+
+blank br:
+
+.Tg blbr
+.br
+Pp blank:
+.Pp
+.Tg Ppbl
+
+blank Pp:
+
+.Tg blPp
+.Pp
+sp blank:
+.sp
+.Tg spbl
+
+blank sp:
+
+.Tg blsp
+.sp
+Double blank:
+
+.Tg blbl
+
+end of file
diff --git a/regress/mdoc/blank/transp.out_ascii b/regress/mdoc/blank/transp.out_ascii
new file mode 100644
index 00000000..f8bdd6b8
--- /dev/null
+++ b/regress/mdoc/blank/transp.out_ascii
@@ -0,0 +1,48 @@
+BLANK-TRANSP(1)             General Commands Manual            BLANK-TRANSP(1)
+
+NNAAMMEE
+     bbllaannkk--ttrraannsspp - transparent nodes between line breaks
+
+DDEESSCCRRIIPPTTIIOONN
+     Double br:
+     br Pp:
+
+     Pp br:
+
+     Double Pp:
+
+     br sp:
+
+     sp br:
+
+     Pp sp:
+
+     Pp sp 2v:
+
+     sp Pp:
+
+
+     Double sp:
+
+
+     br blank:
+
+     blank br:
+
+     Pp blank:
+
+     blank Pp:
+
+
+     sp blank:
+
+
+     blank sp:
+
+
+     Double blank:
+
+
+     end of file
+
+OpenBSD                        February 27, 2020                       OpenBSD
diff --git a/regress/mdoc/blank/transp.out_lint b/regress/mdoc/blank/transp.out_lint
new file mode 100644
index 00000000..533ea600
--- /dev/null
+++ b/regress/mdoc/blank/transp.out_lint
@@ -0,0 +1,19 @@
+mandoc: transp.in:52:1: WARNING: blank line in fill mode, using .sp
+mandoc: transp.in:54:1: WARNING: blank line in fill mode, using .sp
+mandoc: transp.in:60:1: WARNING: blank line in fill mode, using .sp
+mandoc: transp.in:62:1: WARNING: blank line in fill mode, using .sp
+mandoc: transp.in:68:1: WARNING: blank line in fill mode, using .sp
+mandoc: transp.in:70:1: WARNING: blank line in fill mode, using .sp
+mandoc: transp.in:74:1: WARNING: blank line in fill mode, using .sp
+mandoc: transp.in:76:1: WARNING: blank line in fill mode, using .sp
+mandoc: transp.in:12:2: WARNING: skipping paragraph macro: br after br
+mandoc: transp.in:14:2: WARNING: skipping paragraph macro: br before Pp
+mandoc: transp.in:20:2: WARNING: skipping paragraph macro: br after Pp
+mandoc: transp.in:22:2: WARNING: skipping paragraph macro: Pp before Pp
+mandoc: transp.in:26:2: WARNING: skipping paragraph macro: br before sp
+mandoc: transp.in:32:2: WARNING: skipping paragraph macro: br after sp
+mandoc: transp.in:36:2: WARNING: skipping paragraph macro: sp after Pp
+mandoc: transp.in:40:2: WARNING: skipping paragraph macro: sp after Pp
+mandoc: transp.in:50:2: WARNING: skipping paragraph macro: br before sp
+mandoc: transp.in:56:2: WARNING: skipping paragraph macro: br after sp
+mandoc: transp.in:60:1: WARNING: skipping paragraph macro: sp after Pp
diff --git a/regress/mdoc/blank/transp.out_markdown b/regress/mdoc/blank/transp.out_markdown
new file mode 100644
index 00000000..9c8ac825
--- /dev/null
+++ b/regress/mdoc/blank/transp.out_markdown
@@ -0,0 +1,44 @@
+BLANK-TRANSP(1) - General Commands Manual
+
+# NAME
+
+**blank-transp** - transparent nodes between line breaks
+
+# DESCRIPTION
+
+Double br:  
+br Pp:
+
+Pp br:
+
+Double Pp:
+
+br sp:
+
+sp br:
+
+Pp sp:
+
+Pp sp 2v:
+
+sp Pp:
+
+Double sp:
+
+br blank:
+
+blank br:
+
+Pp blank:
+
+blank Pp:
+
+sp blank:
+
+blank sp:
+
+Double blank:
+
+end of file
+
+OpenBSD - February 27, 2020