Table of contents

Appendices

2.9 Standalone Document Declaration

Markup declarations can affect the content of the document, as passed from an XML Processor to an application; examples are attribute defaults and entity declarations. The standalone document declaration, which MAY appear as a component of the XML declaration, signals whether or not there are such declarations which appear external to the Document Entity or in parameter entities. An external markup declaration is defined as a markup declaration occurring in the external subset or in a parameter entity (external or internal, the latter being included because non-validating processors are not required to read them).

In a standalone document declaration, the value yes indicates that there are no External Markup Declaration which affect the information passed from the XML processor to the application. The value no indicates that there are or may be such external markup declarations. Note that the standalone document declaration only denotes the presence of external declarations; the presence, in a document, of references to external entities, when those entities are internally declared, does not change its standalone status.

If there are no external markup declarations, the standalone document declaration has no meaning. If there are external markup declarations but there is no standalone document declaration, the value no is assumed.

Any XML document for which standalone="no" holds can be converted algorithmically to a standalone document, which may be desirable for some network delivery applications.

Validity Constraint: Standalone Document Declaration

The standalone document declaration MUST have the value no if any external markup declarations contain declarations of:

• attributes with Attribute Default values, if elements to which these attributes apply appear in the document without specifications of values for these attributes, or

• entities (other than amp, lt, gt, apos, quot), if Entity Reference to those entities appear in the document, or

• attributes with tokenized types, where the attribute appears in the document with a value such that normalization will produce a different value from that which would be produced in the absence of the declaration, or

• element types with Element content, if white space occurs directly within any instance of those types.

An example XML declaration with a standalone document declaration:

<?xml version="1.1" standalone='yes'?>