There is no intent to exclude concave polygons.  The statement "No three points should be co-linear" was incorrecly transcribed and should be "No three CONSECUTIVE points should be co-linear".
--Ray

> -----Original Message-----
> From: Metadata Object Description Schema List [mailto:[log in to unmask]]
> On Behalf Of Saašha Metsärantala
> Sent: Saturday, July 14, 2012 11:18 AM
> To: [log in to unmask]
> Subject: Re: [MODS] MODS Lat/Long coordinates?
> 
> Hello!
> 
> The MODS guidelines at
> http://www.loc.gov/standards/mods/v3/mods-userguide-elements.html#coordinates
> state
> that:
> 
> > No three points should be co-linear,
> I wonder whether this should be interpreted as an exclusion of polygon
> concavity or if this sentence should be reformulated in the guidelines.
> 
> If concave polygons are allowed, then I consider that three (or more) co-
> linear points should be allowed when these points do not directly follow each
> other.
> 
> Regards!
> 
> Saašha,