According to port-modules, variables starting with MOD* are public, so should get documented, SOONER RATHER THAN LATER.
With the recent make's .VARIABLES addition, bsd.port.mk's dump-vars has gained some introspection capabilities. -current sqlports contains a list of all public module variable values (which is a bit large, and that I'm trying to shrink) So far, the only "big" variables are: MODGO_pre-configure MODGO_SETUP_WORKSPACE MODCARGO_post-extract MODCARGO_post-patch MODCABAL_post-extract MODGO_MODULES MODGO_MODFILES as reported by select distinct(VarName) from ModulesVar where length(value)>50000; we do know that the manifest for go modules is crazy, and bleeds into MODGO_SETUP_WORKSPACE the cargo stuff seems to come from the loops on MODCARGO_CRATES. It can probably be shortened by building a single list of ${_cratename}-${_cratever} and using that in the various targets. Likewise, MODCABAL_post-extract can be halved fairly easily (haven't addressed that yet) Those are valuable changes. Even though make(1) is fairly efficient, building variables thru .for loops happen for *every invocation* of make. You don't get any lazyness points for that... and the manifests for those languages tend to be fairly daunting ! [specifically, using one single .for loop to build one single variable, and then deriving other variables from that will be more efficient: keep in mind that basic variable assignment is lazy and won't be evaluated until the actual target is run, as opposed to basic stuff like "make clean" which has to evaluate ALL FOR LOOPS each and every time] The list of all public variable names follows. Anything NOT documented should be. MODCABAL_BUILD_ARGS MODCABAL_BUILD_TARGET MODCABAL_BUILT_EXECUTABLE_alex MODCABAL_BUILT_EXECUTABLE_cabal-bundler MODCABAL_BUILT_EXECUTABLE_cpphs MODCABAL_BUILT_EXECUTABLE_darcs MODCABAL_BUILT_EXECUTABLE_git-annex MODCABAL_BUILT_EXECUTABLE_happy MODCABAL_BUILT_EXECUTABLE_hasktags MODCABAL_BUILT_EXECUTABLE_hledger MODCABAL_BUILT_EXECUTABLE_pandoc MODCABAL_BUILT_EXECUTABLE_shellcheck MODCABAL_BUILT_EXECUTABLE_xmobar MODCABAL_BUILT_EXECUTABLE_xmonad MODCABAL_DATA_DIR MODCABAL_EXECUTABLES MODCABAL_FLAGS MODCABAL_INSTALL_TARGET MODCABAL_MANIFEST MODCABAL_REVISION MODCABAL_STEM MODCABAL_VERSION MODCABAL_post-extract MODCARGO_BUILD MODCARGO_BUILDDEP MODCARGO_BUILD_ARGS MODCARGO_BUILD_DEPENDS MODCARGO_BUILD_TARGET MODCARGO_CARGOTOML MODCARGO_CARGO_BIN MODCARGO_CARGO_RUN MODCARGO_CARGO_UPDATE MODCARGO_CRATES MODCARGO_CRATES_BUILDDEP MODCARGO_CRATES_KEEP MODCARGO_CRATES_UPDATE MODCARGO_DIST_SUBDIR MODCARGO_ENV MODCARGO_FEATURES MODCARGO_INSTALL MODCARGO_INSTALL_ARGS MODCARGO_INSTALL_TARGET MODCARGO_INSTALL_TARGET_PATH MODCARGO_MASTER_SITESN MODCARGO_NO_DEFAULT_FEATURES MODCARGO_RUSTFLAGS MODCARGO_TARGET_DIR MODCARGO_TEST MODCARGO_TEST_ARGS MODCARGO_TEST_TARGET MODCARGO_VENDOR_DIR MODCARGO_WANTLIB MODCARGO_configure MODCARGO_post-extract MODCARGO_post-patch MODCLANG_ARCHS MODCLANG_CPPWANTLIB MODCLANG_LANGS MODCLANG_VERSION MODCMAKE_BUILD_SUFFIX MODCMAKE_BUILD_TARGET MODCMAKE_DEBUG MODCMAKE_INSTALL_TARGET MODCMAKE_LDFLAGS MODCMAKE_TEST_TARGET MODCMAKE_USE_SHARED_LIBS MODCMAKE_VERBOSE MODCMAKE_WANTCOLOR MODCMAKE_configure MODCPAN_EG_DIR MODCPAN_EXAMPLES MODCPAN_EXAMPLES_DIR MODCPAN_EXAMPLES_DIST MODCPAN_POST_INSTALL MODDCONF_BUILD_DEPENDS MODDCONF_RUN_DEPENDS MODERLANG_post-extract MODERLANG_post-patch MODFONT_do-install MODFORTRAN_BUILD_DEPENDS MODFORTRAN_COMPILER MODFORTRAN_LIB_DEPENDS MODFORTRAN_WANTLIB MODGCC4STDCPP MODGCC4_ARCHS MODGCC4_ATOMICWANTLIB MODGCC4_CPPDEP MODGCC4_CPPLIBDEP MODGCC4_CPPWANTLIB MODGCC4_FORTRANDEP MODGCC4_FORTRANLIBDEP MODGCC4_FORTRANWANTLIB MODGCC4_LANGS MODGCC4_VERSION MODGCONF2_BUILD_DEPENDS MODGCONF2_LIBDEP MODGCONF2_LIB_DEPENDS MODGCONF2_RUN_DEPENDS MODGCONF2_SCHEMAS_DIR MODGCONF2_WANTLIB MODGCONF2_post-patch MODGNOME_BUILD_DEPENDS MODGNOME_CONFIGURE_ARGS_gi MODGNOME_CONFIGURE_ARGS_vala MODGNOME_CPPFLAGS MODGNOME_LDFLAGS MODGNOME_RUN_DEPENDS MODGNOME_TOOLS MODGNOME_pre-configure MODGNUSTEP_IS_FRAMEWORK MODGNUSTEP_LIB_DEPENDS MODGNUSTEP_NEEDS_BACK MODGNUSTEP_NEEDS_BASE MODGNUSTEP_NEEDS_C MODGNUSTEP_NEEDS_GUI MODGNUSTEP_RUN_DEPENDS MODGNUSTEP_WANTLIB MODGNU_AUTOCONF_DEPENDS MODGNU_AUTOMAKE_DEPENDS MODGNU_CONFIG_GUESS_DIRS MODGNU_SAVE_CACHE MODGNU_SAVE_CACHE_LOCATION MODGNU_SHARED_LIBS MODGNU_configure MODGNU_gen MODGO_BINDIR MODGO_BUILDDEP MODGO_BUILD_CMD MODGO_BUILD_DEPENDS MODGO_BUILD_TARGET MODGO_CMD MODGO_DIST_SUBDIR MODGO_FLAGS MODGO_GO111MODULE MODGO_GOCACHE MODGO_GOPATH MODGO_INSTALL_TARGET MODGO_LDFLAGS MODGO_LIST_CMD MODGO_MODFILES MODGO_MODNAME MODGO_MODNAME_ESC MODGO_MODULES MODGO_PACKAGES MODGO_PACKAGE_PATH MODGO_RUN_DEPENDS MODGO_SETUP_WORKSPACE MODGO_SOURCES MODGO_SUBDIR MODGO_TEST_CMD MODGO_TEST_FLAGS MODGO_TEST_TARGET MODGO_TOOLS MODGO_TYPE MODGO_VERSION MODGO_WORKSPACE MODGO_pre-configure MODHEIMDAL_LIB_DEPENDS MODHEIMDAL_WANTLIB MODHEIMDAL_post-patch MODIMAKE_DEPENDS MODIMAKE_configure MODINTLTOOL_OVERRIDE MODJAVA_BUILD MODJAVA_BUILD_ARGS MODJAVA_BUILD_DEPENDS MODJAVA_BUILD_DIR MODJAVA_BUILD_FILE MODJAVA_BUILD_TARGET MODJAVA_BUILD_TARGET_NAME MODJAVA_DOC_DIR MODJAVA_EXAMPLE_DIR MODJAVA_JAR_DIR MODJAVA_JRE MODJAVA_RUN_DEPENDS MODJAVA_SHARE_DIR MODJAVA_VER MODKF5_EXAMPLES_DIR MODKF5_I18N_CONFLICT MODKF5_I18N_CONFLICT-aspell MODKF5_I18N_CONFLICT-hunspell MODKF5_I18N_CONFLICT-locale MODKF5_I18N_CONFLICT-main MODKF5_L10N_CONFLICT MODKF5_L10N_CONFLICT-aspell MODKF5_L10N_CONFLICT-hunspell MODKF5_L10N_CONFLICT-locale MODKF5_L10N_CONFLICT-main MODKF5_VERSION MODKF5_post-install MODLUA_BIN MODLUA_BUILDDEP MODLUA_BUILD_DEPENDS MODLUA_DATADIR MODLUA_DEFAULT_VERSION MODLUA_DEP MODLUA_DEP_VERSION MODLUA_DOCDIR MODLUA_EXAMPLEDIR MODLUA_FLAVOR MODLUA_INCL_DIR MODLUA_LIB MODLUA_LIBDIR MODLUA_LIB_DEPENDS MODLUA_RUNDEP MODLUA_RUN_DEPENDS MODLUA_SA MODLUA_TEST_DEPENDS MODLUA_VERSION MODLUA_WANTLIB MODMARIADB_ADMIN_ARGS MODMARIADB_CLIENT_ARGS MODMARIADB_SERVER_ARGS MODMARIADB_TEST_CMD MODMARIADB_TEST_DBNAME MODMARIADB_TEST_SOCKET MODMARIADB_TEST_TARGET MODMESON_CONFIGURE_ARGS MODMESON_CONFIGURE_ENV MODMESON_WANTCOLOR MODMESON_configure MODMONO_BUILD_DEPENDS MODMONO_DEPS MODMONO_GMCS_COMPAT MODMONO_RUN_DEPENDS MODOCAML_NATDYNLINK MODOCAML_NATIVE MODOCAML_OCAMLDOC MODOCAML_RUNDEP MODOCAML_pre-fake MODPECL_DEFAULTV MODPERL_ADJ_FILES MODPERL_BIN_ADJ MODPERL_BUILD MODPERL_BUILD_TARGET MODPERL_INSTALL_TARGET MODPERL_REGEN_PPPORT MODPERL_TEST_TARGET MODPERL_configure MODPERL_gen MODPERL_pre-configure MODPERL_pre-fake MODPHPSPEC MODPHP_BIN MODPHP_BUILDDEP MODPHP_CONFIGURE_ARGS MODPHP_DO_PHPIZE MODPHP_DO_SAMPLE MODPHP_FLAVOR MODPHP_INCDIR MODPHP_LIBDIR MODPHP_LIB_DEPENDS MODPHP_PDO_ALLOWED MODPHP_PDO_DEPENDS MODPHP_PDO_PREF MODPHP_PHPIZE MODPHP_PHP_CONFIG MODPHP_RUNDEP MODPHP_RUN_DEPENDS MODPHP_VERSION MODPHP_VSPEC MODPHP_WANTLIB MODPOSTGRESQL_TEST_CMD MODPOSTGRESQL_TEST_DBNAME MODPOSTGRESQL_TEST_PGHOST MODPOSTGRESQL_TEST_TARGET MODPYTHON_pre-configure MODQMAKE_ARGS MODQMAKE_ENV MODQMAKE_INSTALL_ROOT MODQMAKE_PROJECTS MODQMAKE_RECURSIVE MODQMAKE_build MODQMAKE_configure MODQMAKE_install MODQMAKE_test MODQT5_BUILD_DEPENDS MODQT5_CONFIGURE_ARGS MODQT5_DEPS MODQT5_INCDIR MODQT5_LIBDIR MODQT5_LIB_DEPENDS MODQT5_LRELEASE MODQT5_LUPDATE MODQT5_MOC MODQT5_OVERRIDE_UIC MODQT5_QMAKE MODQT5_QTDIR MODQT5_UIC MODQT5_USE_CXX11 MODQT5_VERSION MODQT6_DEPS MODQT6_INCDIR MODQT6_LIBDIR MODQT6_LIB_DEPENDS MODQT6_LRELEASE MODQT6_LUPDATE MODQT6_MOC MODQT6_OVERRIDE_UIC MODQT6_QMAKE MODQT6_QTDIR MODQT6_UIC MODQT6_USE_CXX17 MODQT6_VERSION MODRUBY_ADJ_FILES MODRUBY_ADJ_REPLACE MODRUBY_ARCH MODRUBY_BINREV MODRUBY_BIN_RSPEC MODRUBY_BIN_TESTRB MODRUBY_BUILDDEP MODRUBY_BUILD_DEPENDS MODRUBY_BUILD_TARGET MODRUBY_DOCDIR MODRUBY_EXAMPLEDIR MODRUBY_FLAVOR MODRUBY_HANDLE_FLAVORS MODRUBY_INSTALL_TARGET MODRUBY_LIBDIR MODRUBY_LIBREV MODRUBY_LIB_DEPENDS MODRUBY_PKG_PREFIX MODRUBY_RELDOCDIR MODRUBY_RELEXAMPLEDIR MODRUBY_REV MODRUBY_RSPEC3_DEPENDS MODRUBY_RSPEC_DEPENDS MODRUBY_RUBY_ADJ MODRUBY_RUNDEP MODRUBY_RUN_DEPENDS MODRUBY_SITEARCHDIR MODRUBY_SITEDIR MODRUBY_TEST MODRUBY_TEST_BIN MODRUBY_TEST_DIR MODRUBY_TEST_ENV MODRUBY_TEST_TARGET MODRUBY_WANTLIB MODRUBY_pre-configure MODSCONS_BIN MODSCONS_BUILD_TARGET MODSCONS_ENV MODSCONS_FLAGS MODSCONS_INSTALL_TARGET MODTCL_BIN MODTCL_BUILD_DEPENDS MODTCL_CONFIG MODTCL_INCDIR MODTCL_LIB MODTCL_LIBDIR MODTCL_LIB_DEPENDS MODTCL_MODDIR MODTCL_RUN_DEPENDS MODTCL_TCLDIR MODTCL_TCLSH_ADJ MODTCL_VERSION MODTCL_WANTLIB MODTCL_WISH_ADJ MODTK_BIN MODTK_BUILD_DEPENDS MODTK_CONFIG MODTK_INCDIR MODTK_LIB MODTK_LIBDIR MODTK_LIB_DEPENDS MODTK_RUN_DEPENDS MODTK_VERSION MODTK_WANTLIB MODXFCE4_gen MODXFCE4_post-install