# DIMBLK1 System Variable [GstarCAD 2022](Help%20System/GSTARCAD/2022/Index.md) → [System Variables](Help%20System/GSTARCAD/2022/System%20Variables/(System%20Variables).md) → [D](Help%20System/GSTARCAD/2022/System%20Variables/D/(D).md) **Function Description:** The DIMBLK1 system variable is used to set arrowhead for the first end of extension line when the DIMSAH is on. | | | | --- | --- | | Type | Strings | | Saved in | Drawing | | Initial value | "" | Users can enter a Period "." to restore default settings. **Note:** the annotative block can not be used as customized arrow for dimensions and leaders.