I haven't read the Tibetan book of death and dying, so I can't answer that question. So as to what is written in that book I have no idea. Does Theravadin Buddhism, though, have a book or description of the process of dying? I am not aware that there is any kind of description of leaving this body and going into another one. It is mentioned that sometimes it is automatic. The minute you die, you just enter automatically into a womb or into an egg. Or you are spontaneously reborn as another already adult being in a heaven realm and other such things.
They do say that most of the time it is just instant, but at other times the person can get stuck in a type of limbo stage. Their Kamma says, "You should get reborn" but their mind-heart is still grabbing onto their form.
We have a Thai story about one of our teachers and toilets. This is helpful to know. This is from a Thai teacher, you can take it for what it's worth, but this is part of what is taught in Theravadin Buddhism as well.
When this teacher was a young lay man, he worked in monasteries. He was helping build a set of toilets once, and he was working with an older man, who was about 70 years old. As they were building the toilets, before the toilets were done, the old man died. Our teacher said that at that time of his practice he was able to have psychic powers, that he could communicate with invisible beings (take it for what you want). And he thought that he would like to know where the old man got reborn. He felt that since the old man was such a good man, always kept his precepts, meditated very well, was always a good Buddhist, he felt that the old man was probably reborn in a heaven realm. So that night he went into meditation, got very concentrated and developed that ability to see invisible beings, and then he got shocked. He saw the old man floating around the toilets, he wasn't reborn, he was in this "limbo stage", kind of stuck, he was floating around the toilets. You could also call it a kind of ghost state.
Supposedly our teacher said to him, "What are you doing? What are you doing hanging around the toilets? You should be in a heaven realm or good human birth again!". The old man said, "But the toilets aren't finished!" Poof. Our teacher said he completely lost his concentration and came out of meditation, he was so was shocked. The old man was stuck in one of these limbo stages because he was so attached to finishing the toilets. Morning came and our teacher went around telling everybody in the whole village what he had seen in his meditation. Every able-bodied person came to the Wat, and they built and finished the toilets that day. He went back into meditation that night and saw the old man again, who said "Thanks a lot!" and disappeared, going on to his next rebirth. So Theravadin Buddhism does say some people get stuck because they are attached to what they have left behind.
Now, this is also important if you have a relative or friend who dies. We don't want them to feel sad if they are still hanging around. We want to wish them well, go ahead, get reborn, it's okay, we're okay here, you don't have to worry about us. By doing that in meditation - that's what Rosemary and I have done many times with relatives who have died and friends -we feel that we are helping them if they are stuck and can sense what we are thinking. If they are stuck it will make them feel better and then they will be more likely to let go of their attachments.