Data model

Every node of a pyxsd object tree — whether generated from a schema or synthesized by a transform — exposes the same four dunder-prefixed attributes. The double-underscore-free _*_ naming prevents collisions with element or attribute names in your schemas (a schema can legally declare an element called name, so name on an instance always refers to your data, never to metadata).

The shape is codified by the pyxsd.XMLNode runtime-checkable typing.Protocol.

Node structure

Attribute	Type	Meaning
_name_	str	The element name as it appears in the document.
_attribs_	dict[str, str]	Attributes keyed by the name as it should appear in the document. Values are stored lexically; str() must produce the correct output.
_children_	list	Child instances of the same node shape, in document order. Empty list if the element has no children.
_value_	list[str] | None	Non-element content as a list of strings (usually one entry), or None for elements with no text content.

Notes:

• None as _value_ is meaningful: it represents an element nilled with xsi:nil="true", and the writer will emit the nil attribute.

• Attribute defaults applied by validation land in the instance __dict__ (typed values), not in _attribs_, so round-trip output stays faithful.

• Repeated elements (maxOccurs > 1) store every occurrence in _children_ in document order.

Writers

XmlTreeWriter(root, output) serializes any tree of nodes shaped as above. Transform developers commonly use Transform.makeElemObj(name) to mint a fresh node with this exact structure, and makeCommentElem(text) for comments.

Generated classes

Class-level access to descriptors is intentional: item_cls.name returns the descriptor, not the metadata, and the helpful __getattr__ on generated classes raises an AttributeError listing the declared elements and attributes when you misspell something. Instance-level access goes through the descriptors, which validate types on assignment.