# 2.1.1821 Part 4 Section 7.1.2.34, eqArr (Equation-Array Function)

For additional notes that apply to this portion of the standard, please see the notes for oMath, §7.1.2.77(d).

a.   The standard mentions alignment within equation arrays, but never explains how alignment points are specified or how they are used.

There are two types of markers that can be set inside an equation: (1) alignment points and (2) column separators. Both of these markers can be specified by inserting an ampersand character (“&”) in the middle of an equation. An alignment point is inserted to align whatever text comes after it with the rest of the equations at the same alignment points.  [Example: The following diagram depicts an equation array in which the letters x in the condition part are aligned together.

The text that the user should type for these two equations should be:

–x, &x<0

x,&x≥0

end example]

A column separator indicates where white space is added to satisfy the expansion and flush flags, which are provided by the equation array properties maxDist and objDist, respectively. Markers (ampersand character “&”) within an equation are alternately treated as alignment and column separators. Odd-numbered markers are treated as alignment points markers while even markers are treated as column separators. [Example: The following diagram depicts an equation array which has maxDist and objDist both set to on.

The text that the user should type for these two equations should be:

m_11&=n_11&3m_12&=n_12

m_21&=n_21&m_22&=n_22+p_22

In this case, the presence of a single column separator within each equation means there are two columns within the equation array function. After calculating the width of each column, the difference between the formatting width and the sum of the column widths is the column separator. It is this width that causes the two columns to flush left and right. end example]

If the flushing property of the equation array objDist is not specified or specified to be off, space will be allowed at the margins, thus distributing the extra space equally into c + 1 areas, where c is the number of columns.

[Example: The following diagram depicts the same equation array shown in the previous example but it has maxDist set to on and objDist both set to off.

Note that all three columns of space are of equal width. end example]

This note applies to the following products: 2007, 2007 SP1, 2007 SP2.

b.   The standard states that the maxOccurs value for the e child element is unbounded.

Word limits the occurrences of this element to 64.

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