Dear choroba,

Suppose P.P belongs to group 'A', P.P.E belongs to group 'B',,So Id like to have their group names output against them also.

M143:   M143<-M10<-Q = P.P, A
M420:   M420<-M143<-M10<-Q = P.P.E, B
M407:   M407<-M143<-M10<-Q = P.P.PL, C
M10:    M10<-Q = P, D
M421:   M421<-M143<-M10<-Q = P.P.E, B
M406:   M406<-M143<-M10<-Q = P.P.PL, C
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Of course number of groups will be hardly 4 or 5. How can I do it ?