In English, I might say “The dog is beautiful”, and you might reply “This pleases me.” How do you know what “this” refers to? Lojban uses different expressions to convey the possible meanings of the English:
12.1) le gerku [ku] cu melbi The dog is beautiful.
The following three sentences all might translate as “This pleases me.”
12.2) ti [cu] pluka mi This (the dog) pleases me.
12.3) di'u [cu] pluka mi This (the last sentence) pleases me (perhaps because it is grammatical or sounds nice).
12.4) la'e di'u [cu] pluka mi This (the meaning of the last sentence; i.e. that the dog is beautiful) pleases me.Example 12.4 uses one sumti to point to or refer to another by inference. It is common to write “la'edi'u” as a single word; it is used more often than “di'u” by itself.