Excerpt from AC 107-2A - Product Labeling

Product Labeling.
Category 2 and 3. Small UAS qualified for Category 2 or 3 operations must be labeled to
indicate each category for which the small UAS is qualified to operate. The label must be
in English, legible, prominent, and affixed onto the small UA by some permanent means.
A remote pilot is required to ensure his or her small UA is properly labeled before
conducting any operations over people. Because operating limitations apply to operations
under Category 3, the label on the small UA indicating eligibility for operations under
Category 2 and 3 also serves to inform the remote pilot of the operating limitations that
he or she is required to observe.
A person may label the aircraft by any means as long as the label is in the
English language, legible, prominent, and clearly identifies the category of
operations the small UAS may conduct. Because a small UAS could be
qualified to conduct more than one category of operations, the aircraft must be
labeled for each category of operations the small UAS is qualified to conduct.
For example, a manufacturer may use the following labels: “Category 2”,
“Category 3”, “Cat. 2”, or “Cat. 3”. The label could be painted, etched, or
affixed to the aircraft by some other permanent means. The label should be
located where it can easily be seen. The FAA does not prescribe a specific
location for label placement because of the design variations of small
unmanned aircraft. In the case of very small UA, a manufacturer may need to
exercise creativity in determining the location best suited to satisfying the
labeling requirement. Locating a label on a non-critical surface will likely
prevent wear and removal during normal operations.
Because a label may fall off or become illegible, the FAA allows the remote
pilot to re-affix or re-label the aircraft. The remote pilot must ensure the label
remains affixed to the small UA for the duration of the operation.
In addition to the requirement for labeling, a remote pilot must also ensure his
or her small UA is properly labeled before conducting any operations over
people. A clear and legible label is essential for enabling a remote pilot, an
inspector, or a member of the public to identify the types of operations a small
UA may conduct. Accordingly, an aircraft without a clearly legible label
would not be permitted to operate over people. If a label degrades such that it
is no longer legible or attached to the aircraft, the remote pilot is responsible
for providing a new label before operating over people. The labeling
requirement applies regardless of whether a small UAS is obtained directly
from a manufacturer or as a subsequent transfer. No pilot is able to operate the
small UAS unless he or she verifies that the label meets the requirements of
this rule. If the small UAS was manufactured before the effective date of this
rule, or the small UAS was otherwise not labeled, the remote pilot is
responsible for determining whether the FAA has accepted a DoC for that
small UAS. If the aircraft is eligible to operate over people, the remote pilot is
responsible for labeling the aircraft in accordance with this rule.

A label may change if a small UA is modified such that it is qualified to
operate in a different or additional category. If the small UA has been
modified such that it is no longer qualified to operate in its previously labeled
category, the person who performed the modification would have to remove
or cover the previous label so only the label with the newly qualified category
would be visible on the aircraft.