Here is some information you need:
Contains the model database in Pro/MECHANICA Neutral File format, including geometric and Structure-specific entities and parts and part mass properties. Pro/MECHANICA creates this file when you use the MNF command on the Export menu.
Indeed this is an ASCII file. However, there is no analysis results related information (i.e. no mode-shapes) in this file; only geometry and the information Pro/MECHANICA needs to construct the model (loads, constraints, etc.). If you need more information, try searching Google: