This information was given to me by a highly respected Reiki master. I am not personally concerned with specific attributes or functions of symbols, and so I am including the information for those who are interested in this kind of analysis.

CHO KU REI

"Put the Power here."

"God is here."

"Come from the Universe, strengthen the energy."

"Let Power be with me."

"Power of the Universe, come here now."

Cho Ku Rei (or "Cho Ko Rei")  represents the Numeral One (1), and may be called the Empowering Symbol; the Usui Power Symbol: or the Power symbol.

It is the most frequently used Reiki symbol.
About 13 variations of this symbol are known.

Action

Energizing

Opens access to Reiki energy

Energetic amplifier

 Spiritual protection

 Energetic protection (mainly combined with the initiated symbol from Sacred Path Reiki. In this case any clairvoyant can no longer read the energetic fields of a person this symbol has been applied onto.)

 Because of its shape, it focuses the divine energies in one place only

 It focuses the energy

 It accelerates the Reiki flow and increases Reiki power

 Energetic recharging and revitalization

Is like a light switch, or transmission key

Manifesting goals

Sealing energies

 Use:

 When applied on a lesion, it helps the faster healing of this.

 When applied on a painful area, it reduces the pain. 
It can be combined with SHK or symbols from other energetic systems.

When applied in a room, it energetically cleans the room.

When applied on Ajna and Anahata chakras 
(the third eye and the heart), it calms down nervous, irritable people.

 Energizes food, drinks, medicines, crystals, semiprecious stones or jewelry

 It can be programmed to work for 24 hours.

For connecting to the energy source before treatment.

Sealing energies after treatment.

For the creation of a sacred space, used for initiations, treatments or meditations.

When applied with a palm on the other it is equivalent to an attunement and thus one can work on full capacity for about 5 minutes.

Meditation on this symbol can lead to clear-sightedness. In this case one can meditate twice a day, 30 minutes each.

Can be applied on car batteries, electronic devices, telephones, and furniture for increasing their time of use.

Self-treatment: before treatment, the symbol may be applied on the palms and then on every position of the self-treatment.

Distant treatment combined with SHK and HSZSN.

For finding lost objects.

When applied to houseplants, they become more beautiful and disease-resistant.

 Note

 All three symbols have to be applied before starting any treatment, in the next order CKR + SHK + HSZSN.

The place for applying the symbols :

On the therapist’s palms

Directly on the area to be treated, and then palms are applied

On the therapist’s palms, on the area to be treated and then palms are applied

  Above the patient’s head, and then the palms are applied on the desired are

Methods for symbols activation

By drawing them with the palm’s center (with open hand, in this case)

By drawing them with the finger

 By visualizing the symbol

By drawing them with the third eye

By spelling the symbol’s name three times. This last method shall be applied only after a month of daily practice.

 Note. After activation the name of every symbol is spelled three times.