You are using the old World Athletics rule book.
World Athletics approved the use of pacing lights.
From the 2020 Rule book:
Assistance Allowed
6.4 For the purpose of this Rule, the following shall not be considered assistance, and
are therefore allowed:
6.4.1 Communication between the athletes and their coaches not placed in the
competition area.
In order to facilitate this communication and not to disturb the staging of the
competition, a place in the stands, close to the competition area of each
Field Event, should be reserved to the athletes' coaches.
Note: Coaches and other persons otherwise complying with Rules 54.10
and 55.8 of the Technical Rules may communicate with their athlete(s).
6.4.2 Medical examination / treatment and/or physiotherapy necessary to enable
an athlete to participate or continue participation once on the competition
area under Rule 6.1 of the Technical Rules.
6.4.3 Any kind of personal safeguard (e.g. bandage, tape, belt, support, wrist
cooler, breathing aid etc.) for protection and/or medical purposes. The
Referee, in conjunction with the Medical Delegate, shall have the authority
to verify any case should the Referee judge that to be desirable. (See also
Rules 32.4 and 32.5 of the Technical Rules.)
6.4.4 Heart rate or speed distance monitors or stride sensors or similar devices
carried or worn personally by athletes during an event, provided that such
device cannot be used to communicate with any other person.
6.4.5 Viewing by athletes competing in Field Events, of images of previous
trial(s), recorded on their behalf by persons not placed in the competition
area (see Note to Rule 6.1 of the Technical Rules). The viewing device or
images taken from it must not be taken into the competition area.
6.4.6 Hats, gloves, shoes, items of clothing provided to athletes at official stations
or when otherwise approved by the relevant Referee.
6.4.7 Receiving physical support from an official or other person designated by
the organisers to recover to a standing position or to access medical
assistance.
6.4.8 Electronic lights or similar appliance indicating progressive times during a
race, including of a relevant record.