DEFINITION

• If rd(f) is a data on the data format f, rd(f)[k1,...kn] = rd(f)[k1]...rd(f)[kn] where ki > 0 is a virtual segment.
• The data format of the virtual segment rd(f)[k1,...,kn] is f[k1]...f[kn].
• The original data rd is called a real data

EXAMPLE

• Let d(f1) = "34 'T' 'H' 59 11". A virtual segment d(f1) [1,2] is " 34 'T' ".
• Its data format is fi fc