From cb28e8807d7908cc9644c2bd77c9d214dd8caefe Mon Sep 17 00:00:00 2001
From: Hans Hagen <pragma@wxs.nl>
Date: Sun, 21 Mar 2021 22:04:41 +0100
Subject: 2021-03-21 21:08:00

---
 .../manuals/luametatex/luametatex-callbacks.tex       | 19 +++++++++++++++++++
 .../manuals/luametatex/luametatex-enhancements.tex    |  5 +++++
 2 files changed, 24 insertions(+)

(limited to 'doc')

diff --git a/doc/context/sources/general/manuals/luametatex/luametatex-callbacks.tex b/doc/context/sources/general/manuals/luametatex/luametatex-callbacks.tex
index d8e98efa2..f599ac96b 100644
--- a/doc/context/sources/general/manuals/luametatex/luametatex-callbacks.tex
+++ b/doc/context/sources/general/manuals/luametatex/luametatex-callbacks.tex
@@ -719,6 +719,25 @@ font structure.
 Setting this callback to \type {false} is pointless as it will prevent font
 loading completely but will nevertheless generate errors.
 
+\subsection{\cbk {show+whatsit}}
+
+\topicindex{callbacks+whatsits}
+
+Because we only have a generic whatsit it is up to the macro package to provide
+details when tracing them.
+
+\startfunctioncall
+function(<node> whatsit, <number> indentation,
+    <number> tracinglevel, <number> currentlevel, <number> inputlevel)
+    -- no return value
+end
+\stopfunctioncall
+
+The indentation tells how many periods are to be typeset if you want to be
+compatible with the rest of tracing. The tracinglevels indicates if the current
+level and\|/or input level are shown cf. \lpr {tracinglevels}. Of course one
+is free to show whatever in whatever way suits the whatsit best.
+
 \stopsection
 
 \stopchapter
diff --git a/doc/context/sources/general/manuals/luametatex/luametatex-enhancements.tex b/doc/context/sources/general/manuals/luametatex/luametatex-enhancements.tex
index 947b2320a..8a1466301 100644
--- a/doc/context/sources/general/manuals/luametatex/luametatex-enhancements.tex
+++ b/doc/context/sources/general/manuals/luametatex/luametatex-enhancements.tex
@@ -1543,6 +1543,11 @@ related primitives.
 If \prm {tracingonline} is larger than~2, the node list display will also print
 the node number of the nodes.
 
+When bit~1 of \lpr {tracinglevels} is set the current level is prepended to
+tracing lines in the log and when bit~2 is set the input level is prepended. You
+can set both bits and get both numbers prepended. In \CONTEXT\ we default to
+the value~3, so you get prefixes like \type {3:4:} followed by a space.
+
 \stopsubsection
 
 % \startsubsection[title={\lpr {lastnodetype}, \lpr {lastnodesubtype}, \lpr
-- 
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