DTD

DTD VS.XML schemas

DTD

XML schemas

syntax EBNF XML

size compact verbose

have been around ~30 years new

can be parsed no yes

namespaces are not supported supported

data types document-oriented data types data-oriented data types

data types 10 37

occurrences 0, 1 or more.

xx to yy can be specified, but unelegantly and only for small values any number of occurrences can be specified precisely (1 to 3, for example)

enumeration for attributes only for attributes and element content

constraints for attribute values only;

limited set of constraints (fixed value, choices...) rich set of constrains (length, pattern, enumeration, precision, scale...)

defaults for attributes yes yes

attribute grouping no yes

inheritance no yes

extensibility no new data types can be derived

modularity one DTD per document (can be divided into internal and external part) as many schemas per document, as needed

dynamics read-only can be modified at run-time

Mostly from:
Beginning XML. David Hunter, Curt Cagle, Dave Gibbons, Nikola Ozu, Jon Pinnock, Paul Spencer.
Wrox Press Ltd.

	DTD	XML schemas
syntax	EBNF	XML
size	compact	verbose
have been around	~30 years	new
can be parsed	no	yes
namespaces	are not supported	supported
data types	document-oriented data types	data-oriented data types
data types	10	37
occurrences	0, 1 or more. xx to yy can be specified, but unelegantly and only for small values	any number of occurrences can be specified precisely (1 to 3, for example)
enumeration	for attributes only	for attributes and element content
constraints	for attribute values only; limited set of constraints (fixed value, choices...)	rich set of constrains (length, pattern, enumeration, precision, scale...)
defaults for attributes	yes	yes
attribute grouping	no	yes
inheritance	no	yes
extensibility	no	new data types can be derived
modularity	one DTD per document (can be divided into internal and external part)	as many schemas per document, as needed
dynamics	read-only	can be modified at run-time