12.1 Background
 12.2 Contributions to the Result Tree
 12.3 Processing the Source Tree
 12.4 Conditional and Repetitive Processing
 12.5 Variables
 12.6 Attribute Value Templates
 12.7 Procedures (Named Template Rules)
 12.8 Parameters
 12.9 Modes and Priorities
 12.10 Configuration Attributes
 12.11 Imported Files
 12.12 Tips
 12.13 Assignment #7: XSLT