In the Legends of the Five Rings core book, 4th Edition, page 134 (Book of Fire), emphasis mine:
SCHOOL SKILLS are the basic seven Skills taught to a character by his sensei while studying at his clan's School. These vary from School to School, and are specified in the write-ups for the individual Schools in this chapter. Various mechanical effects impact a character's School Skills.
However, I can't find in the Core Book any mention of these mechanical effects. No changes in rolling or raising in the Book of Earth, no changes to purchasing skills and progressing in the Book of Fire, no mention at all in the Book of Water.
What are the various mechanical effects that impact a character's School Skills, in the Core Book? Are there other such effects in official complement content?