Star Of Life

Six-pointed star, outlined with a white border which features the Rod of Asclepius in the center, originally designed and governed by the U.S. National Highway Traffic Safety Administration (NHTSA)
The Star of Life is a cross symbol used by the emergency medical services. It is commonly seen on ambulances and paramedic badges.
It is usually blue and features the familiar medical symbol in the centre; the Rod of Asclepius. (This was originally a pagan symbol but later adopted by Judaism, Christianity and Islam. See Serpent Cross.)
The six arms of the Star of Life represent some of the aspects of emergency medical care: detection of the problem, reporting to the appropriate professionals, response with first aid, on scene care until transportation is available to take the victim to a place with better facilities, care in transit continuing the first aid treatment,transfer to definitive care handing over responsibility

The Tau Cross (Crux Commisa)

The Tau Cross is named from the Hebrew alphabet's last letter 'X', which was pronounced 'Taw'. This same sound transliterates to the Greek letter 'T'. Both the 'X' and 'T' shapes are used in forms of the Chi-Rho Cross.

Tau Cross gets its name from the similarity between letter 'T' and a walking aid. Indeed, the Christian cross is used by many people for their jurney through life.

Crux Commissa means a cross a cross made by joining or attaching pieces together. With the cross bar used as a carring handle, it is called Crux Ansata and represents a attribute of divinity on Egyptian and Assyro-Babylonian sculptures, such as Isis and Osiris. (See aswell the Ankh Cross) It was the symbol of immortality, life in general, and sometimes a phallic symbol. A pagan sign of the mystic Tau of the Chaldeans and the Egyptians, this cross was a attribute of the Roman god Mithras and the Greek Attis, and their forerunner Tammuz, the Sumerian God of Sun, consort of the goddess Ishtar. Conveniently, the original form of the letter 'T' was the initial letter of the god of Tammuz. During baptism, this cross was marked on the foreheads by the pagan priest.