Notation chapter out of date

[dr-shorthair]

In the Notation section on class diagrams it says

Connectors with open arrowheads indicate sub-class relationships, however it should be noted that these are not defined in the SOSA modules — see Expressivity for more explanation.

The 'however' clause is out of date. It should read simply

Connectors with open arrowheads indicate sub-class relationships.