A XML file's property - targetSchema

[Peter]

Hi, I have a question regarding the association between a
XML file and its associated schema file. I define the
steps as below:(from one example of C#, data walkthrough)
* create a schema file first, ie CustomerListSchema.xsd
* create an empty XML file, ie CustomerList.xml
* open the XML file's property window
* in property target, click its dropdown list on the right
* one entry is http://tempuri.org/CustomerListSchema.xsd
* start editing the xml file, guided by the schema file.
Two questions are as below:
1. Please evaborate why http://tempuri.org/...
2. Type Zip is defined as 5 digit positive integer. I type
2 digits, the XML editor of the visual studio still
accepts it. Is this normal?
Please advise. Thanks.