0. ASN.1 grammar parser is written mostly with respect to constructing a tree,
so a tree destruction is not fully supported and certain memory leaks are
known. Not a huge problem for run-once programs like a compiler.
NOTE:	This statement does not apply to the target code _produced_
	by the compiler.

1. REAL type is not supported yet.

2. For purposes of compilation, INTEGER type is modelled using a large
static type (asn_integer_t), but defined as any positive or negative value
by ASN.1. Not a problem as most specifications use very small values anyway.
NOTE:	This statement does not apply to the target code _produced_
	by the compiler.

3. ASN Macros are prohibited by the current ASN.1 standard,
and are not supported.

4. Multiple tags applied at the same level are not supported:
	BadTags ::= [0] EXPLICIT [2] IMPLICIT OtherType
   The same thing could be achieved by using the indirection:
	GoodTags     ::= [0] EXPLICIT OtherTypePtr
	OtherTypePtr ::= [2] IMPLICIT OtherType

5. Mixed definite/indefinite length in a _single_ BER tags sequence is not
supported. Should not be a problem in the real world. Please note that it
is still possible, for example, to encode a wrapper structure using definite
length, and encode its substructure member using indefinite length. The BER
decoder is perfectly capable of decoding such sequences.