Introduction to XML

• The content of an XML file is composed of elements. Each element is marked by a pair of tags <tag>...</tag>.

• The hierarchical structure of elements is important. At the same level of hierarchy, the arrangement order of elements is not important.

• The tag names are keywords, which should not be changed.

• Each element can have multiple attributes, which are name="value" pairs. The names are also keywords. The values must be surrounded by double quotes.

XML Schema

A starter XML schema for PreVABS input files is shipped at prevabs.xsd. It captures the broad structure of:

• Cross-section definition

• Material properties

• Component configurations

• Analysis settings

You can use this schema to validate your input files using any XML validator. For example, using xmllint:

xmllint --schema prevabs.xsd your_input.xml --noout

[!WARNING] The bundled XSD currently lags behind the parser in a few places — for example it does not yet describe type="airfoil" lines, the new <element_shape>/transfinite controls in <general>, the unified recovery <global> block, the transversely isotropic material symmetry class, or the method="join" line composition. The Input Guide is the authoritative reference; the schema is convenient for catching common mistakes but should not be treated as exhaustive.