GN_Lab, Link an alarm block into the alarm chain

Register parameters

RST 20H, DEFW $6C09
 IN:
     BHL = pointer to alarm block (to be linked). 
     Must have been previously allocated by GN_Aab.

OUT, if call successful:
     Fc = 0

OUT, if call failed:
     Fc = 1, time/date already passed
     A = error code:
          RC_BAD ($04), bad parameters

Registers changed after return:
     ..BCDEHL/IXIY same
     AF....../.... different

Notes

A badly formed block is likely to crash the machine. The routine does not check the vality of the alarm block.

Related calls

GN_Aab, allocate alarm block
GN_Alp, process an expired alarm (internal OZ usage)
GN_Fab, free alarm block
GN_Uab, unlink an alarm block from the alarm chain
OS_Alm, alarm manipulation (internal OZ usage)