To eliminate having to change all action 7/9 entries after adding sprites to a .grf file, you can define labels using this action 10. Additionally, this is the only way to skip more than 255 sprites at once.
The data looks as follows:
<sprite-number> * <length> 10 <label> [<comment>]
|<sprite-number>||dec||A sequential sprite number|
|<length>||dec||The total number of bytes in the action|
|<label>||B||Which label to define|
|<comment>||V||Optional comment, ignored by TTDPatch|
The current sprite number.
The total number of bytes in this action 7 or 9.
This sets the number of the label to define. It may range from E0 to FF (allowing 32 labels per grf file).
If two labels are defined with the same number, only the last definition counts.
0.6 2.5 Since TTDPatch 2.0.1 alpha 70, the label may have any number (instead of just E0..FF). In addition, duplicate labels are handled differently, see action 7 for details.