I am going to look really dumb!

[tallboy755]

[color:"blue"] What [color:"red"] is [color:"blue"] a [color:"red"] "portal" [color:"blue"] field! [color:"red"] and [color:"blue"] what [color:"red"] is [color:"blue"] its [color:"red"] functions [color:"blue"] and [color:"red"] purposes.

[trevorg]

I'm going to guess that a "portal field" is simply the related field that resides inside a portal.

I'm assuming you have an understanding of portals. If not, a quick read in the FileMaker online Help should get you aquainted with the concept.

(simply a "window" into a related file's records)