Section 90.135 - Modification of license(a) In addition to those changes listed in § 1.929(k) of this chapter and in accordance with § 1.947 of this chapter the following modifications may be made to an existing authorization without prior Commission approval: (1) Change in the number and location of station control points or of control stations operating below 470 or above 800 MHz meeting the requirements of § 90.119(b) .(2) Change in the number of mobile units operated by Radiolocation Service licensees.(b) Unless specifically exempted in § 90.175 , licensees must submit a Form 601 application for modification to the applicable frequency coordinator for any change listed in § 1.929(c)(4) of this chapter. 65 FR 60875 , Oct. 13, 2000