On Systematic Differences in Individual Solutions and IERS Products Zinovy Malkin Institute of Applied Astronomy RAS, St. Petersburg, Russia 1 Present status Proper determination, modelling, and accounting for systematic differences between contributed series is of the great importance in compilation of the IERS products. ... Possible sources of systematic differences are: · Different reference systems (e.g. TRF, CRF, geopotential, time scale). ... 87 IERS Technical Note No. ...