The "F" in "FEB." is missing its lower bar and therefore looks like an upside-down "L." Since there is not upside-down L on the keyboard - this becomes the "LEB" Error.

Note the errors presented in this series of pictures have official terminology in the price guide. As an example, the price guide references the error shown in "Picture 1" of this series as:

FIELD {E missing middle bar}

When referencing this error (shown in "Picture 1" of this series) instead of saying "The CREB145 error where the "E" in BROOKFIELD is missing its middle bar," it just became easier to say, "Brookficld" (Brook - Fic - ld).