Final answer:
The SMAW electrode limited to horizontal and flat position welding is classified as EXX10, known for its deep penetration and high cellulose sodium coating.
Step-by-step explanation:
The SMAW electrode that is generally restricted to horizontal and flat position welding is EXX10. SMAW, or Shielded Metal Arc Welding, electrodes are classified based on the American Welding Society (AWS) standards, which inform welders of the electrode's usability characteristics, the positions it can weld, and the type of coating it has, among other factors. Electrodes such as the EXX10 series have a high cellulose sodium type of coating, which produces a deeply penetrating arc and is typically used in welding jobs that require deep penetration into the weld joint but are limited in positional welding due to their running characteristics.