What typically denotes the fuel type for stackers in their designation system?

The designation system for stackers often includes a combination of letters and numbers to indicate the fuel type. This alphanumeric coding helps differentiate between various types of fuel sources, such as electric, gasoline, propane, or diesel, while also incorporating other important specifications of the stacker. By using both letters and numbers, the designation system provides a more nuanced understanding of the equipment's capabilities and intended applications.

Using only numbers would be less informative, as it would not convey important details about the fuel type or other specifications. Color coding, while it can help signal different types of equipment or operating statuses, is not as standardized or universally understood as alphanumeric codes. The shape of the frame is primarily a design characteristic and does not inherently convey information about the type of fuel or energy source the stacker operates on. Thus, the combination of letters and numbers is a more effective and recognized method for indicating the fuel type in a stacker's designation.