diff --git a/Known-issues.md b/Known-issues.md
index d606f2c..c9486ae 100644
--- a/Known-issues.md
+++ b/Known-issues.md
@@ -302,7 +302,16 @@ As mentioned above, many clones of ACR112U fail to properly read FeliCa cards. W
 
 Instead of trying to find a good ACR112U unit, you may instead want to look into DIY solutions based on cardIO HID protocol: https://rhythm-cons.wiki/other-hardware/card-readers/
 
-If you have unsupported cards (cards that are NOT FeliCa or old eamuse that start with E004), then use `-scardfix fix` to turn your invalid card into a valid one.
+### Card format supported by games
+
+There are two types of valid cards:
+
+* FeliCa cards
+* ISO15693 cards that start with E004
+
+If you want to use invalid cards, such as MiFare cards, use `-scardfix fix` to convert unsupported cards into one with E004 number.
+
+Really old games do not support FeliCa card numbers, instead they expect all card numbers to begin with E004. If you want to use your FeliCa cards with these old games, use `-scardfix all` to have spice automatically convert your new cards into the old format by prefixing with E004 (and chopping off a few digits at the end).
 
 ## Other issues