According to Wikipedia B-tree page, Knuth's definition fifth property is "All leaves appear in the same level and carry no information.".
What does it mean that they carry no information?
Does that mean that there are no more pointers to children nodes? (kinda redundant to say that as they are the leaves no?)
In the more literal meaning I understand from it that there is actually no information there (AKA the nodes values vs. the key which is used to search) but that doesn't make sense as each key in a B-tree appear only at one node and thus must have a value associated to it or at least a pointer to the data.
Please notice that I'm not referring to a B+ tree where indeed there is an extra layer just for the data/values/information and the keys are indeed duplicated between nodes levels.