Here's how UCD Admission responded to another question in the same thread referred to by collegemom16 ( I think)
"UC GPA" question
"The UC GPA is a weighted GPA for all courses, high school and College level courses, completed in the 10 and 11 grade years. Note that the day after you end your 9 grade year is the start of your 10 grade year; so summer between 9 and 10 grades is counted in the UC GPA. Only UC approved honors courses are considered when weighting the GPA for the first 8 semesters of coursework."