Command of conditional generation "IF"
Syntax
<if>boolean_expression<begin>body<else>body<endif>
boolean_expression = element<and>|<or>|<not>element ...
element = boolean_element|simple filter
boolean_element = p1 operation p2
p1, p2 - parameters
operation - compare operation, can be "=", "~", "<", ">" (ignore double quote)
simple_filter - can contain the next elements, always starts with "+" or "-"

- + ("plus sign") - positive (including) filter
- - ("minus" sign) - negative (excluding) filter, "NOT" operator
- D - derived attributes
- S - simple type attributes
- R - ref key attributes
- C - attributes of class type
- K - key
- E - enumeration attribute
- M0, M1 - mapped attributes
- b - boolean
- 1 - "one" or "zero-one" role cardinality
- * - "zero-many" or "one-many" or "many" role cardinality
- a - role aggregates
- .1 - "one" or "zero-one" opposite role cardinality
- .* - "zero-many" or "one-many" or "many" opposite role cardinality
- .a - opposite role aggregates
- V - void parameters
- X - collection classes
- I - item roles
- A - class of aggregated stereotype
- X - class of collection stereotype (obsolete)