TM 55-1510-221-10
a.
Introductory material.
b.
Indexes and tabular data where the change
cannot be identified.
c.
Blank space resulting from the deletion of
text, an illustration or a table.
d.
Correction of minor inaccuracies, such as
spelling, punctuation, relocation of material, etc.,
unless correction changes the meaning of instructive
information and procedures.
1-11. AIRCRAFT DESIGNATION SYSTEM.
The designation system prescribed by AR 70-50
is used in aircraft designations as follows:
EXAMPLE RC-12H
Within this technical manual the word “shall” is
used to indicate a mandatory requirement. The
word “should” is used to indicate a nonmandatory
but preferred method of accomplishment. The word
“may” is used to indicate an acceptable method of
accomplishment. The word “will” is used to express
a declaration of purpose and may also be used where
simple futurity is required.
1-13. PLACARD ITEMS.
R - Modified mission symbol (Reconnais-
All placard items (switches, controls, etc.) are
sance)
shown throughout this manual in capital letters.
C - Basic mission and type symbol (cargo)
12 - Design number
H - Series symbol
1-12. USE OF WORDS SHALL, WILL, SHOULD,
AND MAY.
1-2
