The journal entry substitution rules can have three types of substitution: substitute with field value, clear field value, or substitute with constant value2. Substitute with field value means that the target field is replaced by the value of another field in the same journal entry item2. Clear field value means that the target field is set to blank2. Substitute with constant value means that the target field is replaced by a fixed value that you enter2. Substitute with formula value and substitute with previous value are not valid substitution types for journal entry substitution rules.