diff --git a/src/file_dat.c b/src/file_dat.c
index 56963bd7..01cbcb36 100644
--- a/src/file_dat.c
+++ b/src/file_dat.c
@@ -31,7 +31,7 @@
 #include "types.h"
 #include "filegen.h"
 
-/*@ requires \valid(file_stat); */
+/*@ requires valid_register_header_check(file_stat); */
 static void register_header_check_dat(file_stat_t *file_stat);
 
 const file_hint_t file_hint_dat= {
@@ -44,15 +44,10 @@ const file_hint_t file_hint_dat= {
 };
 
 /*@
-  @ requires buffer_size > 0;
-  @ requires \valid_read(buffer+(0..buffer_size-1));
-  @ requires valid_file_recovery(file_recovery);
-  @ requires \valid(file_recovery_new);
-  @ requires file_recovery_new->blocksize > 0;
   @ requires separation: \separated(&file_hint_dat, buffer+(..), file_recovery, file_recovery_new);
+  @ requires valid_header_check_param(buffer, buffer_size, safe_header_only, file_recovery, file_recovery_new);
+  @ ensures  valid_header_check_result(\result, file_recovery_new);
   @ assigns  *file_recovery_new;
-  @ ensures \result == 0 || \result == 1;
-  @ ensures  \result!=0 ==> valid_file_recovery(file_recovery_new);
   @*/
 static int header_check_dat(const unsigned char *buffer, const unsigned int buffer_size, const unsigned int safe_header_only, const file_recovery_t *file_recovery, file_recovery_t *file_recovery_new)
 {
@@ -64,14 +59,10 @@ static int header_check_dat(const unsigned char *buffer, const unsigned int buff
 
 /*@
   @ requires buffer_size >= 0x20;
-  @ requires \valid_read(buffer+(0..buffer_size-1));
-  @ requires valid_file_recovery(file_recovery);
-  @ requires \valid(file_recovery_new);
-  @ requires file_recovery_new->blocksize > 0;
   @ requires separation: \separated(&file_hint_dat, buffer+(..), file_recovery, file_recovery_new);
+  @ requires valid_header_check_param(buffer, buffer_size, safe_header_only, file_recovery, file_recovery_new);
+  @ ensures  valid_header_check_result(\result, file_recovery_new);
   @ assigns  *file_recovery_new;
-  @ ensures \result == 0 || \result == 1;
-  @ ensures  \result!=0 ==> valid_file_recovery(file_recovery_new);
   @*/
 static int header_check_datIE(const unsigned char *buffer, const unsigned int buffer_size, const unsigned int safe_header_only, const file_recovery_t *file_recovery, file_recovery_t *file_recovery_new)
 {
@@ -89,14 +80,10 @@ static int header_check_datIE(const unsigned char *buffer, const unsigned int bu
 
 /*@
   @ requires buffer_size >= 0x30+12;
-  @ requires \valid_read(buffer+(0..buffer_size-1));
-  @ requires valid_file_recovery(file_recovery);
-  @ requires \valid(file_recovery_new);
-  @ requires file_recovery_new->blocksize > 0;
   @ requires separation: \separated(&file_hint_dat, buffer+(..), file_recovery, file_recovery_new);
+  @ requires valid_header_check_param(buffer, buffer_size, safe_header_only, file_recovery, file_recovery_new);
+  @ ensures  valid_header_check_result(\result, file_recovery_new);
   @ assigns  *file_recovery_new;
-  @ ensures \result == 0 || \result == 1;
-  @ ensures  \result!=0 ==> valid_file_recovery(file_recovery_new);
   @*/
 static int header_check_dat_history4(const unsigned char *buffer, const unsigned int buffer_size, const unsigned int safe_header_only, const file_recovery_t *file_recovery, file_recovery_t *file_recovery_new)
 {
@@ -110,14 +97,10 @@ static int header_check_dat_history4(const unsigned char *buffer, const unsigned
 
 /*@
   @ requires buffer_size >= 0x36+12;
-  @ requires \valid_read(buffer+(0..buffer_size-1));
-  @ requires valid_file_recovery(file_recovery);
-  @ requires \valid(file_recovery_new);
-  @ requires file_recovery_new->blocksize > 0;
   @ requires separation: \separated(&file_hint_dat, buffer+(..), file_recovery, file_recovery_new);
+  @ requires valid_header_check_param(buffer, buffer_size, safe_header_only, file_recovery, file_recovery_new);
+  @ ensures  valid_header_check_result(\result, file_recovery_new);
   @ assigns  *file_recovery_new;
-  @ ensures \result == 0 || \result == 1;
-  @ ensures  \result!=0 ==> valid_file_recovery(file_recovery_new);
   @*/
 static int header_check_dat_history10(const unsigned char *buffer, const unsigned int buffer_size, const unsigned int safe_header_only, const file_recovery_t *file_recovery, file_recovery_t *file_recovery_new)
 {