This article explains what an EASM file is, how to open it, and how to convert it to another file format.
A file with the EASM file extension is an eDrawings assembly file. It is a representation of a computer-aided design (CAD) drawing, but it is not the complete, editable version of the design.
In other words, one reason EASM files are used is so that clients and other recipients can see the design but not access the design data. They are somewhat similar to Autodesk's DWF format.
Another reason EASM files are used is because they consist of compressed XML data. This makes them the perfect format for sending CAD drawings over the internet where download time/speed is an issue.