These are two settings unique to the legacy Completions Playground, found in the right side parameter panel. They are not required, but can be helpful in simulating chat conversations, where the pattern of back and forth turns requires you to frequently retype the speakers' names.

For example: the Start Text is triggered when a user clicks “Submit”. A new line with the keyword “AI:” is automatically added to the prompt and the completion text begins generating.

Inject Restart Text is used so that the patterned conversation structure continues. At the end of the completion, a new line, with the keyword “Human:”, is automatically added to the end of the prompt. You can then begin typing your human response and continue the flow of conversation.

Note: This feature only exists for legacy Completions and is not supported in the Playground Chat mode.