The grammar to be used in this connection must be very simple. It should consist only of:

• Nouns

• Adjectives

• Verbs

Nouns should be used to specify different physical objects such as generators, motors, transformers, and switches. The verb is used to give the condition of the noun—for example, on, off, running, open, closed. The adjective is used either for

specifying which machine/unit is under discussion, or for giving its characteristics, for example, DC, AC, size. Concrete symbols are suitable for nouns and abstract symbols are best used for verbs (arrows, colours, and so on). Nonfigurative codes such as abbreviations or numbers are best used for adjectives. Figure 3.13 shows the symbol for a lathe chuck. It has a concrete symbol to specify the noun, arrows are used to denote whether the chuck is opening or closing, and numbers and letters specify which lathe the chuck belongs to.