First of all for import to work, Aperture Library has to be updated to Aperture 3.5.1

Below is a list of what is supported

Collections

Aperture Project -> Capture One Project

Aperture Folder -> Capture One  Group

Aperture Album -> Capture One  Album

Any Aperture Projects which directly contain images have a generic sub-album created in CO to contain the images.

Smart Albums, Books, Light Tables, Slideshows, Web Journals, and Web Pages are not imported.

Adjustments

• Straightening 
• Crop (if not Straightened)
• Flip
• Black & White
• Enhance/Definition -> Capture One  Clarity
• Enhance/Saturation -> Capture One  Saturation
• Exposure/Exposure -> Capture One  Exposure
• Exposure/Brightness -> Capture One  Brightness
• Highlights & Shadows (Mid Contrast ignored)

Everything else is ignored.

Metadata

Star Rating

Color Label (note: Ap Grey becomes Capture One Purple)

Applied Keywords (flat, not hierarchical)

IPTC Core Contact: Creator Name, Job Title, Address, City, State/Province, Postal Code, Country, Telephone, Email, Website

IPTC Core Content: Headline, Caption, Keywords, IPTC Subject Code, Caption/Description Writer

IPTC Core Image: Intellectual Genre, IPTC Scene Code, Location, City, State/Province, Country, ISO Country Code

IPTC Core Status: Title, Job Identifier, Instructions, Provider (Credit Line), Source, Copyright, Usage Terms