Used for freeform grids, where some axes may be shared across subplots but others are not. Each entry should be a cartesian subplot id, like *xy* or *x3y2*, or ** to leave that cell empty. You may reuse x axes within the same column, and y axes within the same row. Non-cartesian subplots and traces that support `domain` can place themselves in this grid separately using the `gridcell` attribute.

Used with `yaxes` when the x and y axes are shared across columns and rows. Each entry should be an x axis id like *x*, *x2*, etc., or ** to not put an x axis in that column. Entries other than ** must be unique. Ignored if `subplots` is present. If missing but `yaxes` is present, will generate consecutive IDs.

Used with `yaxes` when the x and y axes are shared across columns and rows. Each entry should be an y axis id like *y*, *y2*, etc., or ** to not put a y axis in that row. Entries other than ** must be unique. Ignored if `subplots` is present. If missing but `xaxes` is present, will generate consecutive IDs.

If no `subplots`, `xaxes`, or `yaxes` are given but we do have `rows` and `columns`, we can generate defaults using consecutive axis IDs, in two ways: *coupled* gives one x axis per column and one y axis per row. *independent* uses a new xy pair for each cell, left-to-right across each row then iterating rows according to `roworder`.

Horizontal space between grid cells, expressed as a fraction of the total width available to one cell. Defaults to 0.1 for coupled-axes grids and 0.2 for independent grids.

Vertical space between grid cells, expressed as a fraction of the total height available to one cell. Defaults to 0.1 for coupled-axes grids and 0.3 for independent grids.

Sets the horizontal domain of this grid subplot (in plot fraction). The first and last cells end exactly at the domain edges, with no grout around the edges.

Sets the vertical domain of this grid subplot (in plot fraction). The first and last cells end exactly at the domain edges, with no grout around the edges.