BAXSELINE, It is not the spelling but the Use of the Word

From the NGS Geodetic Glossary:

"baseline - or (base line) The spelling "baseline" has been adapted by the International Association of Geodesy(IAG), the Journal of Geodesy, the Journal of Surveying Engineering and by many internationally renowned authors who have published numerous texts on Geodesy and other related fields.
(1) (geodesy)A surveyed line established with more than usual care to which surveys are referred for coordination and correlation.
(2) (triangulation) the side of one of a series of connected triangles, the length of which is measured to a prescribed standard of accuracy and from which the lengths of the sides of the other triangles are obtained by computation.
baselines in triangulation are classified according to the character of the work they are intended to control; the instruments and methods used in their measurement assure that the prescribed standards of accuracy are accure. See Federal Geodetic Control Committee (1984).
(3) (construction) The center line of location of a railway or highway. A reference line for the construction of a bridge or other structure. Often called the baseline of location.
(4) A line extending east and west along the astronomic parallel passing through the initial point, along which standard township, section, and quarter-section corners are established.
Such a baseline serves as the starting line for the survey of the meridoinal township boundaries and section lines. Auxiliary governing lines, known as standard parallels or correction lines, are established along the astronomic parallel, usually at intervals of 24 miles north or south of the baseline. In some very early surveys, the baseline is referred to as the basis parallel.
(5) (international law of the sea) The line from which the outer limits of the territorial sea and other offshore zones are measured; the dividing line between inland waters and the territorial sea.
(6) (radio-navigation) The line joining a pair of transmitters in a radio-navigation system."

As I have indicated all uses of the word Baseline indicate a well controlled set of positions.

The Base to Rover GPS vector seldom meets the criteria and most definitely in RTK it does not meet the criteria.

I believe it came from early GPS texts using the word baseline in explanations of solutions of the GPS vector. At that time they were in fact establishing Baselines by very long and multiple occupations. So the result of those calculations was a Baseline, but Baseline is inappropriate to refer to every solved GPS vector.

One might assume that by using the term Baseline for these short time GPS vectors one is in fact prevaricating as to one's work.

You are free to use the term as you please but you would be in a bind were a client to sue that your work does not meet the precision to meet Baseline specifications.

Paul in PA