Yes, you're right: Multi-color does mean that the flower itself has more than one color. All of the potential colors should be checked only when plants produce blooms of completely different colors. In most cases, these are the generic entries. Freesias, for example, can be white, yellow, red, lavender, pink, etc.
The best way to remember the rule is to put yourself in the shoes of the database user. Many people make the mistake of checking each color represented in a multi-colored bloom, checking yellow, white, and red, for instance, if a white bloom has a thin red edge and a yellow center. This should be avoided because a databaase user searching by characteristics for red blooms will not want the results to include flowers that are predominantly white and yellow.
Unfortunately, clarifications in the database template are often ignored. The plant height and width data fields, for instance, ask the contributor to spell out "feet" and "inches" instead of using quotation marks, but many data proposals still use single quotes for feet and double quotes for inches or use abbreviations of feet and inches. Plants defined as "Alpine Gardening" plants in the "Suitable locations" field of the data proposal often don't meet the definition provided in the template clarification.
