In the world of novels," opening a trap " and " filling a trap " usually referred to leaving a suspense or story clue for the reader to look forward to the subsequent development, and then giving an answer or a hint of an answer at the end to guide the reader to continue reading. This process was commonly known as " opening a pit." Sometimes, when a story didn't develop as one expected, one would have to redo or cancel the story clues and suspense that had been left behind. This was called " filling in the hole." " Opening a hole " and " filling a hole " were common phenomena in novel writing.