[css-grid-2] Clarify meaning of "one grid line in each axis"

[gitspeaks]

I'm confused by this line from 7.1. The Explicit Grid:

"If these properties don’t define any explicit tracks, the explicit grid still contains one grid line in each axis."

Since tracks are spaces between two grid lines, having only one line per axis wouldn't form any tracks at all. Can someone explain what the spec means here?

The full paragraph from the spec:

The size of the explicit grid is determined by the larger of the number of rows/columns defined by grid-template-areas and the number of rows/columns sized by grid-template-rows/grid-template-columns. Any rows/columns defined by grid-template-areas but not sized by grid-template-rows/grid-template-columns take their size from the grid-auto-rows/grid-auto-columns properties. If these properties don’t define any explicit tracks the explicit grid still contains one grid line in each axis.

[Loirooriol]

See #5122

[gitspeaks]

I don’t understand why the spec requires a line 1 on each axis when no tracks are defined. What if we used an implicit grid from the start with grid-template-columns/rows: none, where lines are created only when items are placed—like grid-column: 1 generates lines 1 and 2, and grid-column: 5 extends it to lines 1–6? This is similar to how implicit tracks are added beyond the grid’s edge anyway (e.g., grid-column: 10 in a 3-column grid). So why is an initial line 1 necessary instead of just using this implicit approach? What do these starting reference lines actually give us?

[Loirooriol]

It's not necessary. But the difference is observable, and the spec chose this behavior, which is also simpler to implement.

[gitspeaks]

Thanks.