The 69th prohibition is that a kohen who has a blemish is forbidden from entering the entire area of the heichal, i.e., the altar, between the ulam1 and the altar, the ulam, and the heichal itself.
The source of this prohibition is G‑d's statement2 (exalted be He), "But he may not come to the paroches and he may not approach the altar [if he has a blemish]."
In the beginning of Seder Taharos3 it is explained that one who has a blemish or overgrown hair may not enter the area of the heichal beginning with the area between the ulam and the altar. It is also explained in the Sifra that either of these two phrases — "he may not come to the paroches" and "he may not approach the altar" — by themselves would be insufficient. Both are necessary to completely define the extent of this one law4 by defining the exact area where they are forbidden to enter.
One who intentionally went past the altar, even if not to perform the Temple service, is punished by lashes.