diff --git a/src/var.h b/src/var.h
new file mode 100644
index 0000000..ab0fe82
--- /dev/null
+++ b/src/var.h
@@ -0,0 +1,75 @@
+#ifndef _VAR_H
+#define _VAR_H
+
+#include "reg.h"
+#include "mem.h"
+
+/*
+  Variables (or function/procedure) including symbol information are store in the heap
+  The heap segment is a symbol table, too.
+  The heap is the upper region of the data memory.
+*/
+
+/*
+  +----------+ size -1
+  |  data+n  |
+  |  ..      |
+  |  data    | <- addr
+  |  length  |
+  | name[]   | <- top
+  ...
+  +----------+ 0  
+*/
+
+typedef enum {
+  MVAR    = 'V',    // numeric variable or array on the heap    var x,y,z
+#if HAS_FUNC > 0
+  MVARLOC = 'v',    // numeric variable or array on the stack   var* x,y,z : func (a,b,c) { }
+#endif
+  MCONST  = 'C',    // constant value
+  MFUNC   = 'F',    // user defined function reference
+  MPROC   = 'P',    // user defined procedure reference
+  MSTRING = 'S',    // string variable
+  MEVENT  = 'E',    // user defined events, duplicate, but needed because events table need name string stolen from here!
+  MANY    = '*'     // any pattern for heap look-up
+} var_type;
+
+#ifndef VARPADDING
+#define VARPADDING 1
+#endif
+
+typedef struct __attribute__((packed)) {
+  char      name[MAXNAMELEN+1+HAS_LOCK+VARPADDING];
+  var_type  type;
+  index_t   length;   // data length, for proc length is code size, scalar=1, array > 1
+  number_t  data;
+} var_t;
+
+#define var_s   sizeof(var_t)
+// data as an array
+#define VARDATA(v,index) ((number_t*)&v->data)[index]
+
+#if HAS_LOCK>0
+/*
+  variable lock is stored at the end of the name field
+*/
+#define LOCKDATA(v) v->name[MAXNAMELEN+1] 
+#endif
+
+#if HAS_FUNC > 0
+  #define VARLOCLEVEL(x) ((index_t)x&1)
+  #define VARLOCINDEX(x) ((index_t)x>>1)
+  // encode variable address: addr>=0 is heap, addr < -1 is stack
+  #define VARADDRESS(var,addr) var->type==MVARLOC?-(VARLOCINDEX(var->data))-2:addr
+#endif
+
+
+/*
+  Dual use: Allocates variable on heap or resolves address if exists already (and type and length is conforming)
+*/
+
+address_t Allocate(mem_t *M, reg_t *R, char *name, var_type type, index_t length, var_t **v);
+void HeapInit();
+
+#endif
+