The first battlefield blood transfusions were performed in France in 1914 — direct vein to vein, donor to patient, because there was no way to store or pre-screen blood in the field. Blood type was added to American dog tags in 1940. It remains on military identification to this day.
For 86 years, the solution has been a patch on a uniform and a human reading a label.
That patch has never been trusted by the people it is supposed to help. Published research in Military Medicine identified a 3.7% discrepancy rate between soldiers' actual blood type and what was recorded on their identification — with historical error rates as high as 11%. A former blood bank director with forty years of experience stated plainly: many dog tag blood types were wrong, and people were almost never transfused based on that information.
In practice, medics default to O-negative until laboratory confirmation is available. The patch is not a blood identification system. It is an 86-year-old placeholder.
SDICS does not improve on the patch. It replaces it entirely.
11%
Historical error rate for blood type on military dog tags and ID cards. The induction error propagates forward forever. Once wrong, always wrong.
Velcro
Blood type patches are designed to be removed and reattached. There is no verification mechanism. A soldier can be wearing another soldier's patch. Nobody checks.
O-neg
What medics actually use. In practice the patch is ignored and universal donor blood is administered until laboratory confirmation. The patch system is not trusted by its own users.
BBV
The patch shows blood type only. It provides no blood-borne virus screening whatsoever. A compatible blood type from a patch tells the medic nothing about HIV, Hepatitis B, or Hepatitis C.