Fr. James Good sent www.holyname.ie the following explanation of the icon based on his own knowledge of Greek which we reproduce here with his permission.
IHS – We were told as children that it stood for ‘I have suffered’ but in fact it represents the first half of the Holy Name: IHSOUS
IC XC is the normal designation of the name Jesus Christ in Greek shorthand.
ÎC is an abbreviation of IHCOUC which means the same as IHS that is ‘Jesus’
XC stands for XPICTOC which means Christos. This is sometimes also written as :
|(X = Ch; P = R)||Chr|
The Halo – O W N (pronounced HOH OWN) means literally ‘The Being’ giving us the biblical ‘He Who Is’
The Icon is effectively a declaration JESUS CHRIST IS GOD
IHS OR YHS?
The letter ‘I’ or ‘i’ gets various modifications to ornament it- the commonest one being ‘J’ and ‘j’ . The variation used in the Holy Name plaque of St. Bernardine, ‘Y’,is less common. It is a matter of ornamentation. That is all .