The syntax of an instance-method-declaration is:
    '-' [ method-type ] method-selector ';'

The syntax of a method-type is:
    '(' type-name ')'

The syntax of a type-name is the one given by the ISO standards.

The syntax of a method-selector is:
    unary-selector
    keyword-selector [ ',' '...' ] 
    keyword-selector [ ',' parameter-type-list ]

The syntax of a unary-selector is
    selector
with the syntax:
    identifier
as defined by the ISO standards.

The syntax of a keyword-selector is:
    keyword-declarator
    keyword-selector keyword-declarator
where keyword-declarator has the syntax:
    ':' [ method-type ] identifier
    selector ':' [ [method-type] method-type ] identifier