This is a comparison of data serialization formats, various ways to convert complex objects to sequences of bits. It does not include markup languages used exclusively as document file formats.
a. ^ The current default format is binary.
b. ^ The "classic" format is plain text, and an XML format is also supported.
c. ^ Theoretically possible due to abstraction, but no implementation is included.
d. ^ The primary format is binary, but a text format is available.
e. ^ Means that generic tools/libraries know how to encode, decode, and dereference a reference to another piece of data in the same document. A tool may require the IDL file, but no more. Excludes custom, non-standardized referencing techniques.
f. ^ ASN.1 does offer OIDs, a standard format for globally unique identifiers, as well as a standard notation ("absolute reference") for referencing a component of a value. Thus it would be possible to reference a component of an encoded value present in a document by combining an OID (assigned to the document) and an "absolute reference" to the component of the value. However, there is no standard way to indicate that a field contains such an absolute reference. Therefore, a generic ASN.1 tool/library cannot automatically encode/decode/resolve references within a document without help from custom-written program code.
g. ^ VelocyPack offers a value type to store pointers to other VPack items. It is allowed if the VPack data resides in memory, but not if stored on disk or sent over a network.
a. ^ One possible encoding; the specification document does not specifically give an encoding for this datatype.
b. ^ The RFC CSV specification only deals with delimiters, newlines, and quote characters; it does not directly deal with serializing programming data structures.
c. ^ The netstrings specification only deals with nested byte strings; anything else is outside the scope of the specification.
d. ^ PHP will unserialize any floating-point number correctly, but will serialize them to their full decimal expansion. For example, 3.14 will be serialized to 3.140000000000000124344978758017532527446746826171875.
e. ^ XML in and of itself is not a data serialization language, but many data serialization formats have been derived from it; as such, there are many different ways, in addition to those shown, to serialize programming data structures into XML.
f. ^ This syntax is not compatible with the Internet-Draft, but is used by some dialects of Lisp.
It should be noted that any XML based representation can be compressed, or generated as, using EXI - Efficient XML Interchange, which is a "Schema Informed" (as opposed to schema-required, or schema-less) binary compression standard for XML.
