The sum total of the values assigned to all the options in a macro must not exceed 255 bytes, including the option codes and length information. This limit is dictated by the DHCP protocol.
The macros that are most likely to be impacted by this limit are macros that are used to pass paths to files on Solaris installation servers. Generally, you should pass the minimum amount of vendor information needed. You should use short path names in options that require path names. If you create symbolic links to long paths, you can pass the shorter link names.