diff --git a/vm/pc/DECD b/vm/pc/DECD
index 041856d..f276771 100644
--- a/vm/pc/DECD
+++ b/vm/pc/DECD
@@ -13,7 +13,8 @@ LM               R
 M       No more words
 L       LOCK prefix
 R       REP prefix
-D       Destination register
+FT1     First operand format
+FT2     Second operand format
 
 Values for COND:
 00000       (none)
@@ -40,7 +41,7 @@ Fx values:
 0010        imm64
 
 xxx00       [imm64]
-xxx01       [reg+reg]
+xxx01       [reg+reg]                   code(reg)|code(reg)
 xxx10       [reg+reg+imm16]             code(reg)|code(reg)     imm16
 xxx11       [reg+reg*imm16+imm16]       code(reg)|code(reg)     imm16    imm16