FEBRUARY 6 2003
2.6. Letter Spacing Standards. Tile systems are easy to obtain, but there may be times when tiles
are not available. In those situations, use the letter spacing specifications given here for both the
Helvetica medium and the Helvetica regular typefaces. Letter spacing is based on a unit system in
which each unit is equivalent to 1/50th of the capital letter height. Table 2.1 shows the numbers of
spacing units required between characters. Use 20 units between words and 6 units before a
punctuation mark such as a comma, period, semi colon, colon, parentheses, apostrophe, or dash. , . ; :
( )' -. No units are used before or after a diagonal slash (/). An example of correct letter spacing is
seen in Figure 2.3.
2.7. Arrow Tile. Figures 2.4
and 2.5 show the correct proportion
and stroke width for arrows
their proper placement in relation to letters. The dimensions of the arrow tile and letter spacing are
based on the system described in paragraph 2.6, where one unit is 1/50th the height of a capital
letter. Use the standard arrow tile for the Type G3 Pedestrian Information sign and all interior
directional signs. Use the standard Manual on Uniform Traffic Control Devices arrow on all traffic
and directional signs.
2.8. Tile System Application. Air Force signs are laid out by arranging letter and spacing tiles on a
layout grid drawn on the sign face. (A dimensioned layout for each type of sign is given in Chapters
3 through 10.). Tiles are applied to the sign by placing them next to each other and lining up the
alignment notches with the layout lines drawn on the sign face. The sizes of the different signs in the
system are based on multiples of the capital letter height (cap height) of the alphabet to be used in
each sign. All of the layout elements relate to the capital letter height. (See Figure 2.6.) The
maximum tile count given in Figure 2.7 and on the sign layouts in the following chapters indicates
the maximum number of tiles or characters, based on average character widths for upper and lower
case letters and including spaces and punctuation, that can fit on each line of the sign panel.
2.9. Standard Letter Heights. A standard letter height, based on the height of the capital letters
(cap height) of the alphabet used, has been specified for each type of sign. Examples of standard
letter heights used on Air Force signs are illustrated in Figures 2.8 through 2.10. Compare each
alphabet purchased with these standards to make sure that it is correct.
2.10. Sign Assembly Sequence. Signs should be assembled using the sequence shown in Figure
Figure 2.3. Correct Letter Spacing.