Two common cross-classifications within the spectrum of asexuality are based on romantic attraction (some asexuals desire romance with one or more genders, and some don't) and sex drive (some asexuals experience sexual arousal, but without the desire to express it with another person). One way of classifying asexuals is to sort them into the following four basic types:
Type A asexuals, who experience sex drive, but no attraction;
Type B asexuals, who experience romantic or other forms of attraction but do not have sex drives;
Type C asexuals, who experience sex drive and romantic or other forms of attraction, but do not see them as linked;
Type D asexuals, who experience neither.
This classification system was retired, because not all asexual people felt comfortable putting themselves in one of the four categories. However, some still find it useful to reference the concepts of the A, B, C, & D categories at times.
Without the existence of the ABCD classification pointing out obvious differences, it can become easy to lose sight of the great diversity of that asexual people experience. In particular, it can become easy to assume incorrectly that everyone is type D.