Fluid mass density in the orbital plane for different orbital phases, indicated by the inset annotations. An extended WCR is formed due to the interaction of the pulsar (blue) and stellar (orange) wind. The reference frame is co-rotating with the anticlockwise orbital motion. The labels INFC and SUPC correspond to respective parts of the orbit as defined in Fig. 1. The boundaries between the inner and middle regions and between the middle and far regions (further discussed in the text) are indicated by the dashed and dotted lines, respectively.