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a normal entry might be 0 (it is a section offset after all),
and the resulting 0,0 would be taken as end-of-range, not
as a valid entry.
A dwarf dumper would have trouble with such data
in an object file.
.P
In an a.out or shared object (dynamic shared object, DSO)
no text will be at address zero so in such this problem does
not arise.
.H 2 "Section 5.10 Subrange Type Entries problem"
It is specified that  DW_AT_upper_bound (and lower bound)
must be signed entries if there is no object type
info to specify the bound type (Sec 5.10, end of section). 
One cannot tell (with some
dwarf constant types) what the signedness is from the
form itself (like DW_FORM_data1), so it is necessary
to determine the object and type according to the rules 
in 5.10 and then if all that fails, the type is signed.
It's a bit complicated and earlier versions of  mips_extensions
incorrectly said signedness was not defined.
.H 2 "Section 5.5.6 Class Template Instantiations problem"
Lots of room for implementor to canonicalize
template declarations.  Ie various folks won't agree.
This is not serious since a given compiler
will be consistent with itself and  debuggers
will have to cope!
.H 2 "Section 2.4.3.4  # 11. operator spelling"  
DW_OP_add should be DW_OP_plus (page 14)
(this mistake just one place on the page).
.H 2 "No clear specification of C++ static funcs"
There is no clear way to tell if a C++ member function
is a static member or a non-static member function.
(dwarf2read.c in gdb 4.18, for example, has this observation)
.H 2 "Misspelling of DW_AT_const_value"
Twice in appendix 1, DW_AT_const_value is misspelled
as DW_AT_constant_value.
.H 2 "Mistake in Attribute Encodings"
Section 7.5.4, "Attribute Encodings"
has a brief discussion of "constant"
which says there are 6 forms of constants.
It is incorrect in that it fails to mention (or count)
the block forms, which are clearly allowed by
section 4.1 "Data Object Entries" (see entry number 9 in
the numbered list, on constants).
.H 2 "DW_OP_bregx"
The description of DW_OP_bregx in 2.4.3.2 (Register Based
Addressing) is slightly misleading, in that it
lists the offset first.
As section 7.7.1 (Location Expression)
makes clear, in the encoding the register number
comes first.
.H 1 "MIPS attributes"
.H 2 "DW_AT_MIPS_fde"
This extension to Dwarf appears only on subprogram TAGs and has as
its value the offset, in the .debug_frame section, of the fde which
describes the frame of this function.  It is an optimization of
sorts to have this present.

.H 2 "DW_CFA_MIPS_advance_loc8 0x1d"
This obvious extension to dwarf line tables enables encoding of 8 byte
advance_loc values (for cases when such must be relocatable, 
and thus must be full length).  Applicable only to 64-bit objects.

.H 2 "DW_TAG_MIPS_loop        0x4081"
For future use. Not currently emitted.
Places to be emitted and attributes that this might own
not finalized.

.H 2 "DW_AT_MIPS_loop_begin   0x2002"
For future use. Not currently emitted.
Attribute form and content not finalized.

.H 2 "DW_AT_MIPS_tail_loop_begin  0x2003"
For future use. Not currently emitted.
Attribute form and content not finalized.

.H 2 "DW_AT_MIPS_epilog_begin     0x2004"
For future use. Not currently emitted.
Attribute form and content not finalized.

.H 2 "DW_AT_MIPS_loop_unroll_factor  0x2005"
For future use. Not currently emitted.
Attribute form and content not finalized.

.H 2 "DW_AT_MIPS_software_pipeline_depth   0x2006"
For future use. Not currently emitted.
Attribute form and content not finalized.
.H 2 "DW_AT_MIPS_linkage_name                 0x2007"
The rules for mangling C++ names are not part of the
C++ standard and are different for different versions
of C++.  With this extension, the compiler emits
both the DW_AT_name for things with mangled names 
(recall that DW_AT_name is NOT the mangled form)
and also emits DW_AT_MIPS_linkage_name whose value
is the mangled name.
.P
This makes looking for the mangled name in other linker
information straightforward.
It also is passed (by the debugger) to the
libmangle routines to generate names to present to the
debugger user.
.H 2 "DW_AT_MIPS_stride            0x2008"
F90 allows assumed shape arguments and pointers to describe
non-contiguous memory. A (runtime) descriptor contains address,
bounds and stride information - rank and element size is known
during compilation. The extent in each dimension is given by the
bounds in a DW_TAG_subrange_type, but the stride cannot be
represented in conventional dwarf. DW_AT_MIPS_stride was added as
an attribute of a DW_TAG_subrange_type to describe the
location of the stride.
Used in the MIPSpro 7.2 (7.2.1 etc) compilers.
.P
If the stride is constant (ie: can be inferred from the type in the
usual manner) DW_AT_MIPS_stride is absent. 
.P
If DW_AT_MIPS_stride is present, the attribute contains a reference
to a DIE which describes the location holding the stride, and the
DW_AT_stride_size field of DW_TAG_array_type is ignored if
present.  The value of the stride is the number of 
4 byte words between
elements along that axis.