The 'parts' are part of a multi-part vector record (e.g. vectors with donuts or other internal/external nodes making up the vector).

Will you please elaborate it? I have classified vegetation fields. When neighboring fields are connected through a single pixel, the 'Parts' attribute give its value greater than 1. Else if a field is properly discerned and not connected with neighboring fields, then the 'Parts' attribute is equal to 1. On the basis of 'Parts' attribute, can I make adjacently connected fields separate from each other?

Here is a description of multipart vectors if you are not familiar: http://gis.stackexchange.com/question... ArcGIS has many tools for manipulating vectors. In ENVI 5.x, you can open the vector file and select the multipart vector. Choose the Edit Vector tool and then choose 'ungroup' (according to the ENVI Help): "When you ungroup multipart or multipoint records, the row for the multipoint or multipart vector is removed from the table and a new blank row is added for each individual vector."

I got it. Thank you very much :)