10 ILCS 5/5-30
Upon application to vote at a general primary election each registered elector shall sign his name or mark and write his address on a certificate substantially the same as that used in the general election except that it shall have a place for party affiliation which is to be filled in by the elector, or by the officer in charge if the elector is unable to write. The certificates of each State-wide political party at a primary election shall be separately printed upon paper of uniform quality, texture and size, but the certificates of no 2 State-wide political parties shall be of the same color or tint. However, if the election authority provides computer generated applications with the precinct, ballot style and voter's name and address preprinted on the application, a single application may be used for State-wide political parties if it contains spaces or check-off boxes to indicate the political party. Such application shall not entitle the voter to vote in the primary of more than one political party at the same election. Such applications may contain spaces or check-off boxes permitting the voter to request a primary ballot of any other political party which is established only within a political subdivision and for which a primary is conducted on the same election day. Such application shall not entitle the voter to vote in both the primary of the State-wide political party and the primary of the local political party with respect to the offices of the same political subdivision. In no event may a voter vote in more than one State-wide primary on the same day. Such certificates when checked and initialed by the Judge in charge shall constitute the primary poll record. Such certificates at the close of the election shall be placed in an envelope, sealed and returned with the ballots. Nothing herein shall be construed to conflict with sections 7--44 and 7--45 of article 7 of this act. Provided, however, that the applications for ballots made by registered voters under the provisions of article 19 of this act shall be accepted by the Judges of election in lieu of the "certificate of registered voter" provided for in this section.
10 ILCS 5/5-30