The $debug parameter contains a space separated list of flags. Depending on which flags are enabled, various additional debugging messages will be emitted during processing.

The following flags are supported:

callouts

Display additional information about callout processing.

cals-align-char

Display additional information about the computation of character alignment processing in CALS tables.

chunk-cleanup

Display additional information about chunk cleanup processing.

chunks

Display additional information about chunk selection.

db4to5

Display additional information about the DocBook 4.x to 5.x upgrade process.

dynamic-profile

Display additional information about dynamic profiling.

dynamic-profile-suppress

Display additional information about what elements are suppressed by dynamic profiling.

image-properties

Display additional information about the results of the extracting properties from images. This will display all of the properties available from each image.

image-markup

Display the markup generated for media objects.

intra-chunk-links

Display additional information about the resolution of intra-chunk references. to links.

intra-chunk-refs

Display additional information about intra-chunk references.

mediaobject-uris

Display additional information about how media object URIs are constructed.

linkbase

Display additional information about how XLink linkbases are resolved.

localization

Display additional information about localization data.

numeration

Display additional information about how elements are numbered (in titles, in cross references, etc.)

objects

Display additional information about how media objects are selected.

pipeline

Display additional information about the pipeline processing stages.

profile

Display additional information about profiling.

profile-suppress

Display additional information about what elements are suppressed by profiling.

properties

Display additional information about the properties associated with a verbatim environment.

render-verbatim

Display additional information about how verbatim environments are rendered.

tables

Display additional information about how tables are rendered.

template-matches

Display additional information about how title page templates are selected.

templates

Display additional information about title page templates.

verbatim

Display additional information about how verbatim elements are processed.

xlink

Display additional information about XLink resolution.