Specifying additional attribute characteristics

[albena]

Hi there!
I am creating a domain model using logical diagram populated with class elements. Each class has one or more attributes.
For each attribute I can fill in several characteristics such as:
- Name
- Type
- Scope, etc.

These are not enough for me.
In addition I need to specify the following characteristics:
- Length
- Unique
- Not null

How do I do that?
Right now I can say that the attribute is named "Postal code" and is of type String.
But, where do I say that it has exactely 6 characters and must not be null, yet it doesn't need to be unique?

Many thanks for your time and help.
Greets,
Albena

[Geert Bellekens]

Albena,

That's what tagged values were invented for.

Geert

[Eve]

Or, you could use the data modeling profile.

[KP]

Constraints!

(PS are you sure your Postal code attribute is of type String? Or should it be of type PostalCode?)

[qwerty]

For the restrictions: OCL would be the choice.

q.

[albena]

Thanx all of you for the useful answers. Here I am happy to announce my first UML Profile with all the additional tagged values I needed. It works fantastically.
Constraints are also a nice way to realise the same, yet their description is very free style. Do you use any special syntax to describe constraints?

@KP Good point! I should define my own data type PostalCode.

Have fun!

[qwerty]

syntax to describe constraints
 

OCL

q.