This appears to be a HIPAA EDI file. The 271 file layout can be found here (Though there are different versions, it will be important you know what version of the file you have)

http://www.cms.gov/Research-Statistics-Data-and-Systems/CMS-Information-Technology/HETSHelp/downloads/HETS270271CompanionGuide5010.pdf

~ = New "loop" of the data

* = column delimiter

If you go through the guide you will find that the first few characters of each row define what "loop" of data it is, and that then defines what each column means.

On the plus side, the 271 is the simplest of the HIPAA files to work with.