Based on an analysis of the latitude and longitude regularities in the distribution of the sign of the background magnetic field (BMF) on the solar surface for 14 years (1969)(1970)(1971)(1972)(1973)(1974)(1975)(1976)(1977)(1978)(1979)(1980)(1981)(1982), a classification of BMF distributions in the form of synoptic maps, is proposed. That the low-and high-latitude BMF distributions are differing in character appears to be due to the difference in the character of the BMF rotation at low and high latitudes. It is shown that as low-latitude BMF details make contact with the high-latitude field of the same polarity, the former grow in area. The low-and high-latitude fields come into contact through high-latitude field details protruding into lower latitudes as far as 10 to 15 ~ below 40 ~ latitude, and they are referred to as bulges. Bulges and low-latitude fields offike polarity are moving with respect to each other along the E-W line at a mean rate of 10 to 15 ~ per rotation. Bulges of the same polarity in the same hemisphere are moving with respect to each other 3-5 ~ per rotation, on the average. The above-mentioned properties of the structure, interaction and rotation of the low-and high-latitude magnetic field details, taken together, provide a qualitative scheme for the formation and variation of the longitude-regular (sectoral) BMF distribution in the latitude range 40 S-40 N.