BOXHEADS

The boxhead consists of the stubhead, column heads, and spanner heads that classify, describe, or qualify the column or columns to which they refer. The heads are placed approximately in the center of areas defined by real or imaginary lines (boxes) directly above the vertical columns of information to which they apply.

Parts of the Boxhead
The column head is the basic unit of the boxhead, and each column should have one. It may or may not be qualified, supplemented, or described by one or more spanner heads above it.

Spanner heads, or multicolumn heads, are placed above two or more subordinate column heads to clarify, describe, or shorten the subordinate heads (See also Spanners). A single spanner head may also span two or more subordinate spanner heads, as in this example:

In double-page-spread tables, spanners continue from the left-hand to the right-hand page of the pair, with "¾Continued" added following the repeated spanners on the right-hand page.

A banner head, which is a special type of spanner head that is rarely needed, extends over all columns except the stub. The best use of a banner head is as a "read-in" line that clarifies data in the columns in relation to the column heads. In the following example, the banner is appropriate to all data columns and identifies the data shown as different from what the single column heads indicate.

Wording and Punctuation in the Column Head
Column heads should read horizontally¾almost never vertically. Wording is brief, as in other parts of the table, and requires careful phrasing. Horizontal space almost always can be saved by using multicolumn heads, by putting wide heads on more lines, by hyphenating words at the ends of lines, and by using standard, easily understood abbreviations where necessary. (See Breaking and Hyphenating Words.) To avoid an overly formal appearance, capitalize only the first letter of the first word in each head and the first letters of any proper nouns.

Sequence of Columns
Total and subtotal columns are placed at the left of the columns that they aggregate, except in financial tables prepared specifically for accounting purposes, which require totals at the right. In NCES publications intended for broad readership, tables showing dollar amounts have totals on the left. Derived figures¾such as averages, ratios, and percentages¾usually are placed in columns to the right of the base figures.

Spacing in the Column Head
The illustrations following show minimum, normal, and maximum recommended spacing in the boxhead.

In these three examples, the column is approximately centered vertically in the area assigned. For minimum spacing, no blank space is left above or below this head; this spacing should only be used in cases where space is at a premium.

Each column heading in the body of the table should be placed flush right over the column. Within each set of column headings, each column heading should end on the same line. (See Placing Figures in the Column.)

In a ruled table, all of the column-heading boxes on the same level should be the same height, as determined by the column heading with the most typed lines.

Units of Measurement in the Column Head
Units of measurement (e.g., pounds, percent, dollars) often appear in the column head. When they do, they should be placed after or below the column-head captions that they modify. Sometimes a unit of measurement comprises an entire column head.

1. If it modifies a caption, enclose it in parentheses and use all lowercase letters; for example: "Expenditures (millions of dollars)" and "Dollars awarded (in thousands)." Abbreviations, if used, should be clear; for example: "Floor area (1,000 sq. ft.)" or "Floor area (thous. sq. ft.)."
    
2. If it comprises an entire column head, omit the parentheses and treat it like any other column heading. Capitalize, for example, "Billions of dollars" or "Percent of total" if it is the entire head.

Column Numbers or Letters
Occasionally, tables with many column headings need numbered or lettered columns for ease of reference. The numbers or letters appear just below the boxhead and run in sequence from left to right beginning with the stub. Column numbers or letters may be enclosed in parentheses or separated from the rest of the table by a horizontal ruling.

Breaking and Hyphenating Words
Most often in headings (but also in stubs), breaking and hyphenating words is necessary. The guide for breaking words and use of hyphens is the GPO Style Manual and its Word Division Supplement. Comments on some common pitfalls follow:

Break words only between syllables: usually divide doubled
       consonants (e.g., syl- la-bles but en-roll-ments).
 
Never break one-syllable words.
 
Avoid breaking:

Words that would leave a one-letter syllable on a line (not a-mendment).
Words of four or five letters.
 
Always hyphenate as follows:

Full-time equivalents and full-time-equivalent number.
Nondegree-credit students (but noncredit courses and activities).
Nonscience-related curricula.
Nonengineering-related technologies.
First-professional degrees.