tag=>type: content :>url
tag is flowchart’s label ,it is the connecting element in the second part,it can be named randomly,generally it consist of abbreviation of word and numbers
type used to determine label’s type,cause tag is random,so type is sole element to determine the type
there are six type: start end operation subroutine condition inputoutput
only yes or no can be the choice of condition
there is a blank between : and content
take nrg as example: