──┬───────┬─┬─<Boolean value>──────────────────────────────┬───────────┤
├─ NOT ─┤ ├─<Boolean operand>─┬──────────────────────────┤
└─ ^ ───┘ │ └─<partial word part>──────┤
├─<Boolean variable>─┬─ := ──<Boolean primary>─┤
│ └─<update symbols>────────┤
├─<arithmetic relation>────────────────────────┤
├─<Boolean concatenation expression>───────────┤
├─<complex relation>───────────────────────────┤
├─<string relation>────────────────────────────┤
├─<pointer relation>───────────────────────────┤
├─<string expression relation>─────────────────┤
├─<arithmetic table membership>────────────────┤
└─<pointer table membership>───────────────────┘<Boolean operand>
──┬─<Boolean variable>─────────────┬───────────────────────────────────┤ ├─<Boolean function designator>──┤ ├─ ( ──<Boolean expression>── ) ─┤ ├─<Boolean case expression>──────┤ └─<Boolean attribute>────────────┘
<Boolean case expression>
┌◄───────── , ─────────┐ ──<case head>── ( ─┴─<Boolean expression>─┴─ ) ────────────────────────┤
<conditional Boolean expression>
──<if clause>──<Boolean expression>── ELSE ──<Boolean expression>──────┤
The Boolean concatenation expression is described in Concatenation Expression.
The partial word part is described in Partial Word Expression.
The evaluation of a Boolean case expression is described in Case Expression.
