diff --git a/engine/slc.h b/engine/slc.h
index a5ddbd8..7a6e8c8 100644
--- a/engine/slc.h
+++ b/engine/slc.h
@@ -107,6 +107,12 @@ enum SLC_IO_OP {
 };
 typedef enum SLC_IO_OP SLC_IO_OP;
 
+union symptr {
+	uint32_t *varp;
+	wordstart *worp;
+};
+typedef union symptr symptr;
+
 /**
  * Function-abstraction for a "symbol-table".
  *
@@ -123,8 +129,7 @@ typedef enum SLC_IO_OP SLC_IO_OP;
  * @param ptr When adding a found word/variable to the symbol table, the key will point to this wordstart* or uint32_t*
  * @returns The word/var definition stored for the key, or NULL when it is not stored yet or op is SET and there was an error.
  */
-typedef void* (*sym)(SLC_SYM_OP op, char *key, void *ptr);
-// TODO: union for this?
+typedef symptr (*sym)(SLC_SYM_OP op, char *key, symptr ptr);
 
 /**
  * Function-abstraction for an integer "stack".
@@ -161,6 +166,14 @@ typedef uint32_t (*stack)(SLC_STACK_OP op, uint32_t param);
  */
 typedef uint32_t (*session)(SLC_SESSION_OP op, uint32_t i, uint32_t j);
 
+union iores {
+	/** Either the cmd result or the handle pointer*/
+	const char *ptr;
+	/** The read character */
+	char c;
+};
+typedef union iores iores;
+
 /**
  * Function-abstraction for io connectors.
  *
@@ -180,8 +193,7 @@ typedef uint32_t (*session)(SLC_SESSION_OP op, uint32_t i, uint32_t j);
  * @param param The name or temporary name or command or the handle pointer parameter depending on op.
  * @returns A handle pointer or pointer to character to read / written or closed/unlocked handle (NULL on errors). Also cmd stdout.
  */
-typedef const char* (*ioconn)(SLC_IO_OP op, const char *param);
-// TODO: union for this?
+typedef iores (*ioconn)(SLC_IO_OP op, const char *param);
 
 /**
  * Function-abstraction for reading the source code byte-by-byte.