I came across this while trying to build the Yap docs, outside the Boost source tree. It turns out it doesn't work in the Boost source tree either. This: cd ~/boost_1_66_0 ./bootstrap.sh cd libs/units/doc ~/boost_1_66_0/b2 used to work (not sure how long ago). Now it says this: tzlaine@linux-desk:~/boost_1_66_0/libs/units/doc$ ~/boost_1_66_0/b2 Performing configuration checks - 32-bit : no (cached) - 64-bit : yes (cached) - arm : no (cached) - mips1 : no (cached) - power : no (cached) - sparc : no (cached) - x86 : yes (cached) - symlinks supported : yes (cached) BoostBook warning: no DocBook XSL directory specified. If you have the DocBook XSL stylesheets installed, please set DOCBOOK_XSL_DIR to the stylesheet directory on either the command line (via -sDOCBOOK_XSL_DIR=...) or in a Boost.Jam configuration file. The DocBook XSL stylesheets are available here: http://docbook.sourceforge.net/ Stylesheets will be downloaded on-the-fly (very slow!) ...patience... ...patience... ...patience... ...found 2671 targets... ...updating 2 targets... xslt-xsltproc ../../../bin.v2/libs/units/doc/gcc-gnu-7/debug/threadapi-pthread/units.docbook http://docbook.sourceforge.net/release/xsl/current/common/common.xsl:1: parser error : Start ta g expected, '<' not found Project web is currently offline pending the final migration of its data to our ^ compilation error: file /home/tzlaine/boost_1_66_0/tools/boostbook/xsl/docbook.xsl line 12 elem ent import xsl:import : unable to load http://docbook.sourceforge.net/release/xsl/current/common/common.xs l XML_CATALOG_FILES="../../../bin.v2/boostbook_catalog.xml" export XML_CATALOG_FILES "xsltproc" --stringparam boost.defaults "Boost" --stringparam boost.root "../../../.." --strin gparam chunk.section.depth "8" --stringparam toc.max.depth "1" --stringparam toc.section.depth "8" --xinclude -o "../../../bin.v2/libs/units/doc/gcc-gnu-7/debug/threadapi-pthread/units.docbo ok" "/home/tzlaine/boost_1_66_0/tools/boostbook/xsl/docbook.xsl" "../../../bin.v2/libs/units/do c/gcc-gnu-7/debug/threadapi-pthread/units.xml" ...failed xslt-xsltproc ../../../bin.v2/libs/units/doc/gcc-gnu-7/debug/threadapi-pthread/units. docbook... ...skipped <phtml>standalone_HTML.manifest for lack of units.docbook... ...failed updating 1 target... ...skipped 1 target... That's the full output from doing the build a second time, FWIW. Some of the steps the first time said the same thing, but it seemed too much to post. Anyone know what's doing on? Zach