From https://drafts.csswg.org/css-grid/#implicit-grids

The grid-template-rows, grid-template-columns, and grid-template-areas properties define a fixed number of tracks that form the explicit grid.

I'm not convinced about the latter. For example, consider

#grid {
  display: grid;
  grid-template-areas: '. .';
  grid-template-columns: 10px;
  grid-auto-columns: 20px;
}

If the explicit grid has 2 columns due to grid-template-areas, which is the track sizing function of the 2nd one? The spec says that grid-auto-columns is only for implicit tracks!

The grid-auto-rows and grid-auto-columns properties size these implicit grid tracks.

Then https://drafts.csswg.org/css-grid/#propdef-grid-auto-columns seems to redefine implicit tracks in a way that ignores grid-template-areas:

If a grid item is positioned into a row or column that is not explicitly sized by grid-template-rows or grid-template-columns, implicit grid tracks are created to hold it.

I have tested it a bit and it seems that Chromium and Firefox are consistent in this regard:

• Evidence that extra tracks from grid-template-areas are explicit:
  • They are created even if there is no item in them.
  • Extra lines are not considered to have all names in https://drafts.csswg.org/css-grid/#grid-placement-int.
• Evidence that extra tracks from grid-template-areas are implicit:
  • They are sized using grid-auto-columns/rows.
  • They are not included in the resolved value of grid-template-rows/grid-template-columns. [This was reverted due to web compat, now all tracks are included. And not including tracks created with grid-template-areas could have been an overlook.]

So maybe we need a middle concept between explicit and implicit, and define things correctly.