From the Hal6.uhp, I quote:

"The UltraHal function is called by Ultra Hal Assistant 6.0 or a compatible host application. It passes an unformated string of the user's input as well as all remembered variables. The UltraHal function splits the user's input into seperate sentences and then calls GetResponse to get a response for each user sentence. The UltraHal function performs all the initialization functions required for GetResponse so that GetResponse doesn't have to initialize several times if a user inputs more than 1 sentence."