An analysis is presented of the Pioneer 10 and 11 magnetic field data, with regard to the sector structure in the interplanetary magnetic field. For the 3--4 years leading up to the last solar minimum, the data are shown to be consistent with the existence of a wavy equatorial current sheet in the heliosphere. Two sectors are shown to dominate the long term field structure, and each sector is shown to adopt a Parker spiral geometry in the outflowing solar wind. This observation is consistent with the existence of a tilted current sheet that is approximately flat near the sun but that develops a large scale wavy structure owing to the solar rotation. The recurrence pattern of the sector structure suggests an inertial rotation rate of 26.1 days (with a confidence limit of approximately 0.2 day) an observation which may indicate that the source of the low-latitude solar wind is at mid-latitudes on the sun. Corotating interaction regions are shown to be capable of modifying the structure of the current sheet. In particulatr it is suggested that they can absorb the current sheet by overtaking the nearest fold in its wavy structure.