A user tries to include xml tags in the payload but they are ignored.
In this example a defect is created when hitting this endpoint:
https://rally1.rallydev.com/slm/webservice/v2.0/defect/create
The user initially tried the following payload:
{"defect":{"name":"text-xml","description":"<outer>text<inner>text</inner></outer>"}}
which created a defect where Description field did not include xml tags.
To preserve the markup tags use < and > as shown below:
{"defect":{"name":"text-xml","description":"<outer>text<inner>text</inner></outer>"}}
Here is the outcome:
A screenshot from Chrome's Advanced Rest Client shows that API Key in zsessionid header is used for authentication: