Consolidation of co.codes

Hi,

my client has three co.codes 1100,2100,3100. three co.codes has same chat of a/cs and fiscal year and controling area. they are useing same g.l a/cs for three co.codes.

now how the consolidation will do for this three co.codes, pls explan the process of cosolidation and purpose of consolidation. we are useing ECC5 version

Regards,

Balu