What is the main component of a welding symbol that other elements connect to?

The reference line is the central element of a welding symbol from which all other components connect. It serves as a baseline that establishes the orientation and position of the various elements related to the weld. This line is crucial as it provides clarity on how the weld is to be executed, allowing for a standard method of conveying welding information. Other components, such as the weld symbol, tail, and arrow, are placed in relation to this line, creating a comprehensive and organized way to represent welding requirements on engineering drawings. By doing so, the reference line ensures that welders and engineers understand the specifications without ambiguity.