[…] so to speak, at the headwaters of the workstream. Unfinished parts flow downstream from operator to operator, section to section, division to division, until they are assembled, packed and shipped at the stream's end. Such a concept and image has several advantages. It enables one to visualize clearly, and also to plot graphically […] charter on one team was given greater reality because it was implemented by increased interaction along the whole workstream.
Source: wiktionary