Here are some miscellaneous extensions.  Also see the WATCOM_references
specification.

.debug_info extensions:

    AT_WATCOM_pointer_class	0x4080
	This attribute is used in AT_pointer_type or AT_reference_type and
	has a constant value which is a bitfield with the following values:
	    PTR_default		0
	    PTR_near		1
	    PTR_far		2
	    PTR_huge		3
	    PTR_far16		4

    AT_WATCOM_segment	0x4081
	TAG_pointer_type
	TAG_reference_type
	    AT_WATCOM_segment is a location expression that calculates the
	    segment portion of the pointer (for based pointers).   It expects
	    the segment/address of the pointer itself to be pushed on the
	    stack (for based(_self)).

	Any other tag with a location expression that calculates the address of
	an object, or an AT_low_pc or AT_high_pc:
	    AT_WATCOM_segment is a location expression that calculates
	    the segment portion of the address.

    AT_mod_u_d_type, AT_mod_fund_type
	Have the following additional modifiers:
	    MOD_near	0x80
	    MOD_far	0x81
	    MOD_huge	0x82
	    MOD_far16	0x83


.debug_macinfo extensions:
    MACINFO_vend_ext
	    followed by line number ULEB128
	    0x01    indicates references
		    followed by null-terminated macro name which is used
		    on this line
		    -- this has been proposed... 92.08.djg2
			The proposal has a different structure; it asks
			for a new record MACINFO_reference.
