5. TYPE OF CHARACTERS FOR NATIONALITY,
COMMON AND REGISTRATION MARKS
5.1 The letters shall be capital letters in Roman characters
without ornamentation. Numbers shall be Arabic numbers
without ornamentation.
5.2 The width of each character (except the letter I and
the number 1) and the length of hyphens shall be two-thirds of
the height of a character.
5.3 The characters and hyphens shall be formed by solid
lines and shall be of a colour contrasting clearly with the background.
The thickness of the lines shall be one-sixth of the
height of a character.
5.4 Each character shall be separated from that which it
immediately precedes or follows, by a space of not less than
one-quarter of a character width. A hyphen shall be regarded
as a character for this purpose.
6. REGISTER OF NATIONALITY,
COMMON AND REGISTRATION MARKS
Each Contracting State or common mark registering authority
shall maintain a current register showing for each aircraft
registered by that State or common mark registering authority,
the information recorded in the certificate of registration (see
Section 7). The register of unmanned free balloons shall
contain the date, time and location of release, the type of
balloon and the name of the operator.