How do you read the weld dimension if the symbol a or z not mentioned?

If the weld dimension symbol "a" (length of the weld) or "z" (throat thickness) is not mentioned, you typically refer to the standard weld size specified in the welding procedure or code applicable to the project. The default dimensions may be implied based on the type of joint and the material being welded. Always consult relevant standards or specifications to ensure compliance with the required weld sizes and types. If in doubt, it's advisable to clarify with the design or engineering team.