diff --git a/internal/inst/types.go b/internal/inst/types.go
index c0b10e2..20b6f2f 100644
--- a/internal/inst/types.go
+++ b/internal/inst/types.go
@@ -7,8 +7,9 @@ type Instruction struct {
 }
 
 type Form struct {
-	Operands []Operand
-	CPUID    []string
+	ISA              []string
+	Operands         []Operand
+	ImplicitOperands []Operand
 }
 
 type Operand struct {
@@ -16,6 +17,11 @@ type Operand struct {
 	Action Action
 }
 
+type ImplicitOperand struct {
+	Register string
+	Action   Action
+}
+
 type Action uint8
 
 const (
diff --git a/internal/load/load.go b/internal/load/load.go
index 9e9b3bc..0bba60d 100644
--- a/internal/load/load.go
+++ b/internal/load/load.go
@@ -81,10 +81,6 @@ func (l *Loader) init() error {
 		return err
 	}
 
-	// for a, op := range l.alias {
-	// 	log.Printf("alias %#v -> %s", a, op)
-	// }
-
 	l.order = opcodescsv.BuildOrderMap(icsv)
 
 	return nil
@@ -279,8 +275,24 @@ func (l Loader) form(opcode string, f opcodesxml.Form) inst.Form {
 		ops[0].Type = "imm2u"
 	}
 
+	// Extract implicit operands.
+	var implicits []inst.ImplicitOperand
+	for _, implicit := range f.ImplicitOperands {
+		implicits = append(implicits, inst.ImplicitOperand{
+			Register: implicit.ID,
+			Action:   inst.ActionFromReadWrite(implicit.Input, implicit.Output),
+		})
+	}
+
+	// Extract ISA flags.
+	var isas []string
+	for _, isa := range f.ISA {
+		isas = append(isas, isa.ID)
+	}
+
 	return inst.Form{
 		Operands: ops,
+		ISA:      isas,
 	}
 }