Crossword Clue:

They can be indicated by a or

Answer	Crossword Clue
IONS	They can be indicated by a + or -
BRASIZES	They can be denoted by a number and a letter
MEDIA	They can be a musician's friend or enemy

SETS	They can be decided by tiebreakers
CAPITALS	They can be produced by shifting
TVS	They can be controlled by remote controls
OMENS	They can be read by the illiterate