The PROPS Tag

The PROPS Tag
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The PROPS tag and the PROPERTY tags inside it are used to define mode-specific properties. Each PROPERTY tag must have a NAME attribute set to the property's name, and a VALUE attribute with the property's value.

All buffer-local properties listed in the section called “Buffer-Local Properties” may be given values in edit modes.

The following mode properties specify commenting strings:

commentEnd - the comment end string, used by the Range Comment command.
commentStart - the comment start string, used by the Range Comment command.
lineComment - the line comment string, used by the Line Comment command.

When performing auto indent, a number of mode properties determine the resulting indent level:

The line and the one before it are scanned for brackets listed in the indentCloseBrackets and indentOpenBrackets properties. Opening brackets in the previous line increase indent.
If lineUpClosingBracket is set to true, then closing brackets on the current line will line up with the line containing the matching opening bracket. For example, in Java mode lineUpClosingBracket is set to true, resulting in brackets being indented like so:
```
{
    // Code
    {
        // More code
    }
}
```
If lineUpClosingBracket is set to false, the line after a closing bracket will be lined up with the line containing the matching opening bracket. For example, in Lisp mode lineUpClosingBracket is set to false, resulting in brackets being indented like so:
```
(foo 'a-parameter
    (crazy-p)
    (bar baz ()))
(print "hello world")
```
If the previous line contains no opening brackets, or if the doubleBracketIndent property is set to true, the previous line is checked against the regular expressions in the indentNextLine and indentNextLines properties. If the previous line matches the former, the indent of the current line is increased and the subsequent line is shifted back again. If the previous line matches the latter, the indent of the current and subsequent lines is increased.
In Java mode, for example, the indentNextLine property is set to match control structures such as “if”, “else”, “while”, and so on.
The doubleBracketIndent property, if set to the default of false, results in code indented like so:
```
while(objects.hasNext())
{
    Object next = objects.hasNext();
    if(next instanceof Paintable)
        next.paint(g);
}
```
On the other hand, settings this property to “true” will give the following result:
```
while(objects.hasNext())
    {
        Object next = objects.hasNext();
        if(next instanceof Paintable)
            next.paint(g);
    }
```

Here is the complete <PROPS> tag for Java mode:

<PROPS>
    <PROPERTY NAME="commentStart" VALUE="/*" />
    <PROPERTY NAME="commentEnd" VALUE="*/" />
    <PROPERTY NAME="lineComment" VALUE="//" />
    <PROPERTY NAME="wordBreakChars" VALUE=",+-=&lt;&gt;/?^&amp;*" />

    <!-- Auto indent -->
    <PROPERTY NAME="indentOpenBrackets" VALUE="{" />
    <PROPERTY NAME="indentCloseBrackets" VALUE="}" />
    <PROPERTY NAME="unalignedOpenBrackets" VALUE="(" />
    <PROPERTY NAME="unalignedCloseBrackets" VALUE=")" />
    <PROPERTY NAME="indentNextLine"
    	VALUE="\s*(((if|while)\s*\(|else\s*|else\s+if\s*\(|for\s*\(.*\))[^{;]*)" />
    <PROPERTY NAME="unindentThisLine"
    	VALUE="^.*(default:\s*|case.*:.*)$" />
    <PROPERTY NAME="electricKeys" VALUE=":" />
    <!-- set this to 'true' if you want to use GNU coding style -->
    <PROPERTY NAME="doubleBracketIndent" VALUE="false" />
    <PROPERTY NAME="lineUpClosingBracket" VALUE="true" />
</PROPS>