Is there a standard naming convention for XML elem

Question

Is there any standard, de facto or otherwise, for XML documents? For example which is the "best" way to write a tag?

<MyTag />
<myTag />
<mytag />
<my-tag />
<my_tag />

Likewise if I have an enumerated value for an attribute which is better

<myTag attribute="value one"/>
<myTag attribute="ValueOne"/>
<myTag attribute="value-one"/>

Answer 1

Many document centred XML dialects use lower case basic Latin and dash. I tend to go with that.

Code generators which maps XML directly to programming language identifiers are brittle, and (with the exception of naive object serialisation, such as XAML) should be avoided in portable document formats; for best reuse and information longevity the XML should try to match the domain, not the implementation.

Answer 2

I suspect the most common values would be camelCased - i.e.

<myTag someAttribute="someValue"/>

In particular, the spaces cause a few glitches if mixed with code-generators (i.e. to [de]serialize xml to objects), since not many languages allow enums with spaces (demanding a mapping between the two).

Answer 3

I normally align XML naming convention with the same naming convention in other parts of code. The reason is when I load the XML into Object its attributes and element names can be referred as the same naming convention currently used in the project.

For example, if your javascript using camelCase then your XML uses camelCase as well.

Answer 4

Microsoft embraces two convention:

1. For configuration, Microsoft uses camelCase. Look at Visual Studio config file. For VS2013, it is stored in:

   C:\Program Files (x86)\Microsoft Visual Studio 12.0\Common7\IDE\devenv.exe.config

Example:

<startup useLegacyV2RuntimeActivationPolicy="true">
  <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.5" />
</startup>

2. Microsoft also uses UpperCase for their XAML. I guess it is to differentiate from HTML (which uses lowercase).

Example:

<MenuItem Header="Open..." Command="ApplicationCommands.Open">
    <MenuItem.Icon>
        <Image Source="/Images/folder-horizontal-open.png" />
    </MenuItem.Icon>
</MenuItem>

Answer 5

XML Naming Rules

XML elements must follow these naming rules:

    - Element names are case-sensitive 
    - Element names must start with a letter or underscore
    - Element names cannot start with the letters xml(or XML, or Xml, etc) 
    - Element names can contain letters, digits, hyphens, underscores, and periods 
    - Element names cannot contain spaces

Any name can be used, no words are reserved (except xml).

Best Naming Practices

    - Create descriptive names, like this: <person>, <firstname>, <lastname>.
    - Create short and simple names, like this: <book_title> not like this: <the_title_of_the_book>.
    - Avoid "-". If you name something "first-name", some software may think you want to subtract "name" from "first".
    - Avoid ".". If you name something "first.name", some software may think that "name" is a property of the object "first".
    - Avoid ":". Colons are reserved for namespaces (more later).
    - Non-English letters like éòá are perfectly legal in XML, but watch out for problems if your software doesn't support them.

Naming Styles

There are no naming styles defined for XML elements. But here are some commonly used:

    - Lower case    <firstname> All letters lower case
    - Upper case    <FIRSTNAME> All letters upper case
    - Underscore    <first_name>    Underscore separates words
    - Pascal case   <FirstName> Uppercase first letter in each word
    - Camel case    <firstName> Uppercase first letter in each word except the first

reference http://www.w3schools.com/xml/xml_elements.asp

Answer 6

I have been searching a lot for a good approach, also reading this thread and some others and I would vote for using hyphens.

They are used broadly in ARIA ( https://developer.mozilla.org/de/docs/Web/Barrierefreiheit/ARIA ) which can be seen in many source codes and are therefore common. As already pointed out here, they are certainly allowed, which is also explained here: Using - in XML element name

Also as a side benefit: When writing HTML in combination with CSS, you often have classes whose names use hyphens as separator by default as well. Now, if you have custom tags that use CSS classes or custom attributes for tags that use CSS classes, then something like:

<custom-tag class="some-css-class">

is more consistent and reads - in my humble opinion - much nicer than:

<customTag class="some-css-class">