The British Standard for weld symbols is BS EN 22553.    When identification of the weld process is required as part of the weld symbol the relevant weld process code is listed in BS EN ISO 4063.

The weld symbol always includes

1. An arrow line
2. A reference line
3. A symbol

Note: Weld symbols on the full reference line relates to welds on the near side of the plate being welded.   Weld symbols on the dashed line relates to weld on the far side of the plate.   If the welds are symmetrical on both sides of the plate the dashed line is omitted. If the dashed line is above the full line then the symbol for the nearside weld is drawn below the reference line and the symbol for the farside weld is above the dashed line