Hal is derived from hallucination being more profound to the specter of telepathy. In hallucinations you have a person that by his own mind he or she makes a halucination very real.
Hal should be a mix of vision, halucination and telepathy in which the subject would hear what the other person has thought and by further saying the tought the person that had a hal would confirm what the subject has tought and said.
The reality of halucination, vision and hal is difficult to understand. Hals are toughts that by further investigation are being considered reality in its own person mind.
Example: The person had hals about our planet system and the parallel universe. In its own mind he produced an idea that our planet is being aligned with another parallel universe or system. Few years later the person reads about the same thing from a news paper confirming his hals to be true.
The person can have other hals like speaking to non existing species. This by modern science is considered a halucination but on the other hand if the person does some research on the subject he or she could be well convinced it was a reality.
Example: The person could have hals with other species in which they could during the exchange say to the person: We are Thot and this is a preparation. The subject that never heard of its subject in reality could than go to investigate what did he or she heard about and by typing the word Thot in the search engine he or she would be given a great tree of knowledge leading him to greater understanding of him self and the world he or she came from.