22.1.2.3 aln

This element specifies the alignment property on the box object. It is utilized only when the box is designated as an operator emulator. When 1 or true, this operator emulator serves as an alignment point; that is, designated alignment points in other equations can be aligned with it.

When the element is absent, the default is for the parent structure to not be an alignment point.

When the element is present and the val attribute is absent, the default value of the val attribute is 1 meaning that this property’s parent structure is an alignment point.

[Example: For example, the following equation uses the operator emulator as an alignment point: 𝑎 == 𝑏.

Its XML representation is as follows:

<m:oMath>
  <m:r>
    <m:t>a</m:t>
  </m:r>
  <m:box>
    <m:boxPr>
      <m:opEmu m:val="1"/>
      <m:aln m:val="1"/>
      <m:ctrlPr/>
    </m:boxPr>
    <m:e>
      <m:r>
        <m:t>==</m:t>
      </m:r>
    </m:e>
  </m:box>
  <m:r>
    <m:t>b</m:t>
  </m:r>
</m:oMath>

end example]

[Example:

Given the following equations:

Their associated XML represenation is as follows:

<m:oMathPara>
  <m:oMath>
    <m:r>
      <m:t>a+b</m:t>
    </m:r>
    <m:r>
      <m:rPr>
        <m:aln/>
      </m:rPr>
      <m:t>-c=2</m:t>
    </m:r>
    <m:r>
      <m:rPr>
        <m:sty m:val="p"/>
      </m:rPr>
      <w:br/>
    </m:r>
  </m:oMath>
  <m:oMath>
    <m:r>
      <m:t>x</m:t>
    </m:r>
    <m:r>
      <m:rPr>
        <m:aln/>
      </m:rPr>
      <m:t>-y+z=3</m:t>
    </m:r>
  </m:oMath>
</m:oMathPara>

The subtraction symbols in each of the above equations have been identified as alignment points, so the equations are aligned at their subtraction symbols (because they are in the same Math paragraph).

end example]

Attributes

val (value)

Specifies a binary value for the property defined by the parent XML element.

A value of 1 or true specifies that the property shall be explicitly applied. This is the default value for this attribute, and is implied when the parent element is present.

A value of 0 or false specifies that the property shall be explicitly turned off. This is implied when the parent element is not present.

The possible values for this attribute are defined by the ST_OnOff simple type (22.9.2.7).

[Note: The W3C XML Schema definition of this element’s content model (CT_OnOff) is located in A.6.1. end note]