This is now covered in section 3.2.

Each animation listed by name should have a corresponding value for the other animation properties listed below. If the lists of values for the other animation properties do not have the same length, the length of the ‘animation-name’ list determines the number of items in each list examined when starting animations. The lists are matched up from the first value: excess values at the end are not used. If one of the other properties doesn't have enough comma-separated values to match the number of values of ‘animation-name’, the UA must calculate its used value by repeating the list of values until there are enough. This truncation or repetition does not affect the computed value. Note: This is analogous to the behavior of the ‘background-*’properties, with ‘background-image’ analogous to ‘animation-name’.