This page applies to Harlequin v13.1r0 and later; and to Harlequin Core but not Harlequin MultiRIP
With a single exception (concerning the %pagebuffer% device), devices are not permitted to allocate memory from the Harlequin Core memory. However, this field can be used to request the Harlequin Core to allocate memory when setting up the device, and this memory can then be used by the device.
When a new device is set up by the Harlequin Core, it allocates sizeof_private bytes of memory and zeroes it. If no per-device memory is required for a particular device type, sizeof_private should be set to 0.