url-mime-separator-chars

url-mime-separator-chars is a variable defined in `url-vars.el'.
Its value is

(65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 48 49 50 51 52 53 54 55 56 57 39 40 41 43 95 44 45 46 47 61 63)

Documentation:
Characters allowable in a MIME multipart separator.