Version history

SnakeGrid was originally known as RailGrid. When the name was changed (to reflect common usage since it was based on the Snake Projection, and applies to more uses than rail) the version sequencing was maintained. Consequently the versions are:

 

RailGrid v1	Internal prototype, not formally released.
RailGrid v2	First application, only applicable to the London to Glasgow West Coast Main Line, the grid being referred to as WCG05.
RailGrid v3	First generic version, requiring an input parameter file.
SnakeGrid v4.0.1	Re-development of the algorithms to incorporate several new features, in particular faster processing speeds and more flexible grid designs. Used for all new grids from 2008 onwards.
SnakeGrid v4.0.2	Minor update to the v4.0.1 algorithm. An improvement of the v4 algorithms to give better scale factor characteristics at large distances from the trend line. To be used on grids developed after April 2016.
SnakeGrid_ASA	The Alternative SnakeGrid Algorithms. When SnakeGrid v4.0.1 was developed, it was not possible to maintain backward compatibility with previous versions, and hence the new algorithms could not read the old parameter files. This has now been overcome by developing “ASA” parameter files for the older grids, which can be read by the ASA algorithm. There are sometimes reasons to use ASA algorithms with more recent grids, for example when handling grids merged at a junction.
SnakeGrid v4.1	This is simply a combination of the above algorithms, which is able to identify whether a parameter file is a standard v4 one (and so call the v.4.0.1 algorithms) or an ASA one (and so call the ASA algorithms).
SnakeGrid v4.1.1	An update to v4.1, incorporating the v4.0.2 sub-algorithm. Hence v4.1.1 is able to identify whether a parameter file is a standard v4 one (and so call the v.4.0.1/v4.0.2 algorithms) or an ASA one (and so call the ASA algorithms).