The following interface variables are defined automatically by abuild:

ABUILD_STDOUT_IS_TTY: boolean indicating whether or not standard
output is a terminal; potentially useful in test environments

ABUILD_ITEM_NAME: the name of the current item
ABUILD_TREE_NAME: the name of the current item's tree
ABUILD_TARGET_TYPE: the target type of the current item
ABUILD_PLATFORM_TYPE: the platform type of the current item
ABUILD_OUTPUT_DIR: the output directory of the current item/platform
ABUILD_PLATFORM: the platform of the current build of the current item

For object-code build items, these variables provide access to the
individual fields of the platform string:

ABUILD_PLATFORM_OS string
ABUILD_PLATFORM_CPU string
ABUILD_PLATFORM_TOOLSET string
ABUILD_PLATFORM_COMPILER string
ABUILD_PLATFORM_OPTION string

The following variables are used by C/C++ rules.  You can assign to
them in your Abuild.interface files.  You can also append to them in
Abuild.mk if needed, though it's usually not recommended.  If you do,
you should use +=, rather than = or :=, in order to avoid overriding
assignments made in your dependencies' interface files.

declare INCLUDES -- include directories
declare LIBS -- libraries specified without the "-l"
declare LIBDIRS -- library directories
declare XCPPFLAGS -- extra flags passed to the C preprocessor
declare XCFLAGS -- extra flags passed to the C compiler
declare XCXXFLAGS -- extra flags passed to the C++ compiler
declare XLINKFLAGS -- extra flags passed to the linker

For java build items, these variables are also defined:

abuild.classpath -- items used at compile-time, run-time, and in packaging
abuild.classpath.external -- used at compile-time but not in packaging
abuild.classpath.manifest -- to be included in the manifest of direct
       reverse dependencies

The abuild.classpath.manifest variable "non-recursive", meaning you
only see assignments made to it your own build item and in those on
which you directly declare dependencies.  You do not see assignments
made to it by your indirect dependencies.

If you declare any optional dependencies, for each optional dependency
"item" that you declare, a variable called

  ABUILD_HAVE_OPTIONAL_DEP_item

is declared as a local variable.  You have access to it in your own
Abuild.interface, but it will not be visible to items that depend on
your item.