pwr power/intensity images
.meta metaspectral images in which a sigle file contains multiple stacked bands
.db indicates the unit of the intensity image (decibels)
.series a time series of raster images which contains multiple rasters
.cut represents an image produced from subsetting a previous image via sample selection
module
.Int refers to a non-flattened interferogram
.Dint refers to a flattened differential interferogram interferogram

I was looking for a guide that identifies what each file format represents, and which is readable by envi for further processing, but I couldn't find any.