Help reqd in shell scripting..

Hi guys,
I am new to shell scripting and I need urgent assistance.
I have an xml like :
<AgreementNumberFull>13-WY-84252</AgreementNumberFull>
<AgreementNumberAbbr>WY84252</AgreementNumberAbbr>
<LineOfBusiness>F</LineOfBusiness>
<CompanyCode>0005</CompanyCode>
<UniqDigit/>
<StateCode/>

I need to write a script which parses this xml and returns the value of tags in string data type. If the value of the tag is null(eg:UniqDigit) then response string should be '0'
The output for the above xml should be:
13-WY-84252
WY84252
F
0005
0
0.

Please help me with this.

I'd suggest looking at perl and using a dedicated XML parsing module to do this, or giving awk a go
If you have to do it in shell script it will go a lot easier if you can guarantee that each tag will be on a single line.