Main Principles

Main principles of describing trucks and their components in XML files are the following:

The names of tags, attributes, and values are case-sensitive.
All values of attributes, including numeric values, must be in quotation marks.
XML has a hierarchy of tags. Any tag has its own place in the general hierarchy and must not violate it.
Each opened tag must be closed.
- If a tag is located on the lowest level of hierarchy and, correspondingly, has no children tags, it is written in the form similar to:
```
<TagName Attr1="a" Attr2="b" />
```
- If a tag has children tags, it is written in the form similar to:
```
<TagName Attr1="a" Attr2="b">
    Children Tags
</TagName>
```
The order of tags that are located on the same level in hierarchy is typically not important. However, there are exceptions from this rule that are described separately.
Each tag has its own particular set of attributes. Any attribute of a tag can be either mandatory or optional.
Tags with the same name, but with different parent tags, have different purposes.
You can use common and local templates (_templates) in the XML file.
An XML file can be inherited from another XML file (_parent) that is located in the same folder.

TIP 1: Most of popular tags and their attributes are described in the Tags and Attributes of Trucks.

TIP 2: The hierachy of sections and topics within Tags and Attributes of Trucks corresponds to the hierarchy of these tags.