Should Crossrail be included as a "tube line"?

by papanek

Given that crossrail trains are heavy rail, largly opperate on national rail infrastructure, and the Elizebeth line has it's own roundel brnading (like other tfl modes e.g. the DLR, the Overground, Emerates Air Line etc...) a case can be made that it does not count as a conventional 'tube' line, and shouldn't be classed as one