One of the frustrations I have with filling out my address in web forms is the postal code field. Often, it is not a problem, but regularly, there are problems. For example, a form for a US-based company may indicate they accept Canadian addresses, but their zip code field is restricted to five characters (the length of a basic US zip code). Another example is a field that restricts the input to six characters.
Here is an example of a Canadian postal code:
T0K 0K0
Notice the space. That is the standard format: three-character pattern, space, three-character pattern. That is seven characters.
Please let me enter the postal code how I want, and at the very least in the standard format set by Canada Post.