Thank you for your inquiry. The available data type is subject to the database you selected for your project (Tools > DB > Database Configuration). In case you wish to model with the non-standard data type then you can reference to the article below about how it works.
Set data types for the columns in a database model table
1.Double-click the shape for the table that has the columns that you want to set data types for.
In the Database Properties window, under Categories, click Columns.
Click the cell in the Data Type column that you want to change.
Click the down arrow next to the current data type and choose a different data type from the list.
Customizing programming language and data types[b]
By default, there are six types of predefined (programming) languages. Each of them consists of a set of supported data types.
Open the Project Options window by selecting Window > Project Options from the main menu.
Choose Data Type from the list on the left hand side of the Project Options window.
In the Data Type page, click the + button under Languages: to add a language.
Enter its name, and press OK button to confirm.
Press Add… button to add a data-type to the chosen language.
Enter its name and press OK to confirm. From now on, once you have set your own language as the language for your project, you can pickup the associated data-types as attribute type, operation return type and parameter type.
in ER diagram each element have different representation. The datatype is an important element of database. We can get data type visible in the entity box and changes in setting on diagram level in right way