only. Change symbols, such as a number sign (#), plus
mark (+), black circle, black square, and the letters C,
R, or X are explained in the introductory portion of the
manual. Change symbols are not used for the
following:
Introductory material
Indexes and tabular data where the change
cannot be identified
Blank space resulting from the deletion of text,
an illustration, part of an illustration or a table
Correction of minor inaccuracies, such as
spelling, punctuation, relocation of material,
renumbering of paragraphs, etc., unless such
correction changes the meaning of instructive
information or procedures
Replacement or addition of a complete part,
chapter, or section
Changes to illustrations, line drawings, and
photographs are normally identified by a miniature
pointing hand. This hand points to the general area of
change information, as shown in figure 2-11. Changes
confined to the same general area are indicated only
once on the illustration. A vertical line next to changed
material may be used on a chart or graph. In the
illustrated parts breakdown of technical manuals, the
illustrations have no change symbols.
Shading and screening are used for diagrams and
schematics to highlight the areas containing the
changed information. Shading is put in the direct area
of the change. Extensively changed information may
be indicated by a screen border around the affected
area (fig. 2-12). For microfilm, however, no screening
is used.
Difference Data Sheets. Difference data sheets
(fig. 2-13) allow data to be added to or changed
without making a direct impact on the existing
information. These sheets reflect minor changes in the
basic design. A separate sheet is prepared and issued
for each additional configuration or model covered.
The format of difference data sheets is as follows:
Sheets are identified by the title DIFFERENCE
DATA SHEET centered at the top of each page.
The first page of each sheet (for a specific model)
has a heading in uppercase type, which consists of the
nomenclature and the model, type, or part number of the
item covered. The heading is followed by a statement to
this effect: THE INSTRUCTIONS CONTAINED IN
THE PRECEDING SECTIONS OF THIS
Figure 2-10.—Change symbol, vertical line.
Figure 2-11.—Change symbol, miniature pointing hand.
2-10
