Weird use of PRIM_LINK_TARGET?

listOfPrimLinkTargetItems = [];
listOfPrimLinkTargetItems +=
[
  PRIM_LINK_TARGET, LINK_SET, PRIM_ALPHA_MODE, 3, PRIM_ALPHA_MODE_MASK, 128
];
listOfPrimLinkTargetItems +=
[
  4, LINK_SET, PRIM_ALPHA_MODE, 3, PRIM_ALPHA_MODE_BLEND, 0
];
listOfPrimLinkTargetItems +=
[
  1, LINK_SET, PRIM_ALPHA_MODE, 3, PRIM_ALPHA_MODE_BLEND, 0
];
listOfPrimLinkTargetItems +=
[
  2, LINK_SET, PRIM_ALPHA_MODE, 3, PRIM_ALPHA_MODE_BLEND, 0
];
listOfPrimLinkTargetItems +=
[
  3, LINK_SET, PRIM_ALPHA_MODE, 3, PRIM_ALPHA_MODE_BLEND, 0
];

llSetLinkPrimitiveParamsFast(999, listOfPrimLinkTargetItems);