iCloud limits max size of contact group

iCloud now posts a useful webpage describing its limits. http://support.apple.com/kb/HT4489?viewlocale=en_US&locale=en_US

Oddly, it lists the maximum size of a Contact Group as 256kb. That's the same limit it has for a single contact card. So what does that mean?

Most of my groups when exported are files of many MBs.