When `dragmode` is set to *select*, this limits the selection of the drag to horizontal, vertical or diagonal. *h* only allows horizontal selection, *v* only vertical, *d* only diagonal and *any* sets no limit.

The number of rows in the grid. If you provide a 2D `subplots` array or a `yaxes` array, its length is used as the default. But it's also possible to have a different length, if you want to leave a row at the end for non-cartesian subplots.

Is the first row the top or the bottom? Note that columns are always enumerated from left to right.

The number of columns in the grid. If you provide a 2D `subplots` array, the length of its longest row is used as the default. If you give an `xaxes` array, its length is used as the default. But it's also possible to have a different length, if you want to leave a row at the end for non-cartesian subplots.

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`.