Types

A decision table of this type having only the symbols "Y"(es), "N"(o) or "-" (irrelevance indicator) in the condition display part and only "X" or "-" in the action display part is generally designated as a limited entry decision table.

Each condition is fully described in the condition part so that in the condition display part – just like a question – it is only to be answered with Y or N indicators. If the condition for the execution of actions is irrelevant, "-” is entered as a condition indicator.

Every action is completely described in the action part so that it only needs to be ticked in the action display part if it is to be e­xe­cu­ted. Actions are e­xe­cu­ted from top to bottom in the sequence as ticked.

A limited entry simple decision table only uses Y/N as a condition indicator.

A limited entry complex decision table uses Y/N/- as a condition indicator.

Extended entry decision tables are used if the conditions on the left-hand side of the condition part are incomplete and extensions are entered as condition indicators on the right-hand side of the condition display part.

The left-hand part of the decision table as such will not suffice for a complete definition of such conditions and actions. They are only completely defined along with the right-hand part of the table and are called extended conditions and actions.

Extended entry decision tables should be used whenever a variable (such as age, color, etc.) can take on different values that are mutually exclusive. The number of condition and action lines is reduced and complex situations can be displayed clearly in a small space.

If the presentation of a limited entry decision table is linked to an extended entry decision table, a mixed decision table is produced.

See also: Extended conditions and actions

An unambiguous decision table is a decision table in which no case is determined by several rules.

An ambiguous decision table is a decision table in which at least one case is determined by several rules.

However, the consistency of ambiguous decision tables is not as systematically verifiable as is the case with unambiguous decision tables.

This is the reason why LF‑ET does not support this decision table type.