diff --git a/README.md b/README.md
index a1a7af6..5529078 100644
--- a/README.md
+++ b/README.md
@@ -378,7 +378,6 @@ in two distinct groups `iter1` and `iter2`.
   To see your `h5` file in readable file format, you can check the section
   [Comparison with the `h5dump` command](#compare_h5_h5dump).
 
-
 ### Ex6. Simplifying the code
 
 As you can notice, the %PDI code is quite redundant.
@@ -428,6 +427,81 @@ In summary:
 \attention
 The `::PDI_multi_expose` is implemented with interlaced share/reclaim pairs.
 
+\attention
+When we used `::PDI_multi_expose` with multiple data, the order of appearance
+of the arguments of the function corresponds to the order of the `::PDI_share`.
+
+\attention
+To gain a better understanding of the information provided by the trace plugin,
+the call order of different "share" is changed in the ex6 after the main loop.
+
+The order of share is important when we used a metadata. To demonstrate this,
+we decompose `::PDI_multi_expose`.
+
+In the exercise 6, after the main loop, the data `main_field` is shared
+before the variable `ii`:
+```C
+// end of the main loop
+PDI_share("main_field", cur, PDI_OUT); // event "on_data" for "main_field"
+PDI_share("ii",         &ii, PDI_OUT); // update the metadata ii in PDI to 4
+PDI_event("finalization");
+PDI_reclaim("ii");
+PDI_reclaim("main_field");
+```
+
+At the end of the main loop, `ii` is equal to 4. Therefore, `cur` corresponds
+to the value of `main_field` at iteration 4.
+
+As `ii` is a metadata, the value is stored by pdi. This value correspond to
+the last value of `ii` shared with pdi. Hence, at the end of the main loop,
+this value is equal to the value of the previous iteration 3.
+
+In `::PDI_share`, an event "on_data" on the shared data is automatically
+performed. An example of this event is
+```yaml
+decl_hdf5:
+    - file: ex6-final-iteration.h5
+      write: [ main_field ]
+      when: '$ii=4'
+```
+This event is done when we call
+```C
+PDI_share("main_field", cur, PDI_OUT); // event "on_data" for "main_field"
+```
+But at this moment, the value of `ii` in pdi is still the value of the previous iteration 3.
+Therefore, the file `ex6-final-iteration.h5` is not writing on the disk.
+
+To solve this issue, we need to change the order of the `::PDI_share`:
+```C
+PDI_share("ii",         &ii, PDI_OUT); // update the metadata ii in PDI to 4
+PDI_share("main_field", cur, PDI_OUT); // event "on_data" for "main_field"
+PDI_event("finalization");
+PDI_reclaim("main_field");
+PDI_reclaim("ii");
+```
+
+or with `::PDI_multi_expose`:
+
+```C
+PDI_multi_expose("finalization",
+          "ii",         &ii, PDI_OUT,
+          "main_field", cur, PDI_OUT,
+          NULL);
+```
+
+\attention
+In a `::PDI_multi_expose` if you have a data1 that depend on the data2.
+You need to pass the arguments corresponding to data2 before the arguments
+corresponding to data1 in this function.
+
+For example, a vector `V` that depends on its size `N`:
+```C
+PDI_multi_expose("save_vector_V",
+          "size_of_vector", &N, PDI_OUT,
+          "vector_V", V, PDI_OUT,
+          NULL);
+```
+
 ### Ex7. Writing a selection
 
 In this exercise, you will only write a selection of the 2D array in memory
diff --git a/ex10.c b/ex10.c
index 44fcf75..7c51a4b 100644
--- a/ex10.c
+++ b/ex10.c
@@ -227,9 +227,9 @@ int main( int argc, char* argv[] )
 	}
 	// finally share the main field as well as the loop counter after the loop
 	PDI_multi_expose("finalization",
-	        "ii",         &ii, PDI_OUT,
-	        "main_field", cur, PDI_OUT,
-	        NULL);
+			"ii",         &ii, PDI_OUT,
+			"main_field", cur, PDI_OUT,
+			NULL);
 	
 	// finalize PDI
 	PDI_finalize();
diff --git a/ex11.c b/ex11.c
index aba49e2..fd0d6a3 100644
--- a/ex11.c
+++ b/ex11.c
@@ -300,9 +300,9 @@ int main( int argc, char* argv[] )
 	}
 	// finally share the main field as well as the loop counter after the loop
 	PDI_multi_expose("finalization",
-	        "ii",         &ii, PDI_OUT,
-	        "main_field", cur, PDI_OUT,
-	        NULL);
+			"ii",         &ii, PDI_OUT,
+			"main_field", cur, PDI_OUT,
+			NULL);
 	
 	// finalize PDI
 	PDI_finalize();
diff --git a/ex12.c b/ex12.c
index fb39968..0c6a5b1 100644
--- a/ex12.c
+++ b/ex12.c
@@ -282,9 +282,9 @@ int main( int argc, char* argv[] )
 	}
 	// finally share the main field as well as the loop counter after the loop
 	PDI_multi_expose("finalization",
-	        "ii",         &ii, PDI_OUT,
-	        "main_field", cur, PDI_OUT,
-	        NULL);
+			"ii",         &ii, PDI_OUT,
+			"main_field", cur, PDI_OUT,
+			NULL);
 	
 	// close the file should_output.dat
 	close_file();
diff --git a/ex3.c b/ex3.c
index fd3d7e1..10289a1 100644
--- a/ex3.c
+++ b/ex3.c
@@ -213,10 +213,10 @@ int main( int argc, char* argv[] )
 	// the main loop
 	for (; ii<10; ++ii) {
 		// share the loop counter & main field at each iteration
-		PDI_share("ii", &ii, PDI_OUT);
-		PDI_reclaim("ii");
+		PDI_share("ii",         &ii, PDI_OUT);
 		PDI_share("main_field", cur, PDI_OUT);
 		PDI_reclaim("main_field");
+		PDI_reclaim("ii");
 		
 		// compute the values for the next iteration
 		iter(cur, next);
diff --git a/ex4.c b/ex4.c
index 1816e1a..eb16797 100644
--- a/ex4.c
+++ b/ex4.c
@@ -228,9 +228,9 @@ int main( int argc, char* argv[] )
 		double (*tmp)[dsize[1]] = cur; cur = next; next = tmp;
 	}
 	// finally share the loop counter and main field after the main loop body
-	PDI_share("main_field", cur, PDI_OUT);
-	PDI_share("ii",         &ii, PDI_OUT);
+	PDI_share("ii", &ii, PDI_OUT);
 	PDI_reclaim("ii");
+	PDI_share("main_field", cur, PDI_OUT);
 	PDI_reclaim("main_field");
 	
 	// finalize PDI
diff --git a/ex5.c b/ex5.c
index 43f1f82..322e66b 100644
--- a/ex5.c
+++ b/ex5.c
@@ -231,10 +231,10 @@ int main( int argc, char* argv[] )
 		// swap the current and next values
 		double (*tmp)[dsize[1]] = cur; cur = next; next = tmp;
 	}
-	// // finally share the loop counter and main field after the main loop body
-	PDI_share("main_field", cur, PDI_OUT);
-	PDI_share("ii",         &ii, PDI_OUT);
+	// finally share the loop counter and main field after the main loop body
+	PDI_share("ii", &ii, PDI_OUT);
 	PDI_reclaim("ii");
+	PDI_share("main_field", cur, PDI_OUT);
 	PDI_reclaim("main_field");
 	
 	// finalize PDI
diff --git a/ex6.c b/ex6.c
index ed12ba8..bac3d8f 100644
--- a/ex6.c
+++ b/ex6.c
@@ -236,11 +236,11 @@ int main( int argc, char* argv[] )
 	// finally share the main field as well as the loop counter after the loop
 	//*** use PDI_multi_expose to replace PDI_share + event + reclaim
 	//...
-	PDI_share("ii",         &ii, PDI_OUT);
 	PDI_share("main_field", cur, PDI_OUT);
+	PDI_share("ii",         &ii, PDI_OUT);
 	PDI_event("finalization");
-	PDI_reclaim("main_field");
 	PDI_reclaim("ii");
+	PDI_reclaim("main_field");
 	
 	// finalize PDI
 	PDI_finalize();
diff --git a/ex7.c b/ex7.c
index babdf3e..dbba767 100644
--- a/ex7.c
+++ b/ex7.c
@@ -227,9 +227,9 @@ int main( int argc, char* argv[] )
 	}
 	// finally share the main field as well as the loop counter after the loop
 	PDI_multi_expose("finalization",
-	        "main_field", cur, PDI_OUT,
-	        "ii",         &ii, PDI_OUT,
-	        NULL);
+			"ii",         &ii, PDI_OUT,
+			"main_field", cur, PDI_OUT,
+			NULL);
 	
 	// finalize PDI
 	PDI_finalize();
diff --git a/ex8.c b/ex8.c
index 96cbc53..31ad786 100644
--- a/ex8.c
+++ b/ex8.c
@@ -227,9 +227,9 @@ int main( int argc, char* argv[] )
 	}
 	// finally share the main field as well as the loop counter after the loop
 	PDI_multi_expose("finalization",
-	        "main_field", cur, PDI_OUT,
-	        "ii",         &ii, PDI_OUT,
-	        NULL);
+			"ii",         &ii, PDI_OUT,
+			"main_field", cur, PDI_OUT,
+			NULL);
 	
 	// finalize PDI
 	PDI_finalize();
diff --git a/ex9.c b/ex9.c
index b7d20c1..e254438 100644
--- a/ex9.c
+++ b/ex9.c
@@ -227,9 +227,9 @@ int main( int argc, char* argv[] )
 	}
 	// finally share the main field as well as the loop counter after the loop
 	PDI_multi_expose("finalization",
-	        "main_field", cur, PDI_OUT,
-	        "ii",         &ii, PDI_OUT,
-	        NULL);
+			"ii",         &ii, PDI_OUT,
+			"main_field", cur, PDI_OUT,
+			NULL);
 	
 	// finalize PDI
 	PDI_finalize();
diff --git a/solutions/ex12.yml b/solutions/ex12.yml
index 7d12327..450ecac 100644
--- a/solutions/ex12.yml
+++ b/solutions/ex12.yml
@@ -11,7 +11,7 @@ pdi:
     dsize: { type: array, subtype: int, size: 2 }
     psize: { type: array, subtype: int, size: 2 }
     pcoord: { type: array, subtype: int, size: 2 }
-    should_output: logical
+    should_output: int
     switch: int
   data: # values for which PDI does not keep a copy
     main_field: { type: array, subtype: double, size: [ '$dsize[0]', '$dsize[1]' ] }
diff --git a/solutions/ex2.c b/solutions/ex2.c
index ef38ea8..0560cfd 100644
--- a/solutions/ex2.c
+++ b/solutions/ex2.c
@@ -229,7 +229,7 @@ int main( int argc, char* argv[] )
 		// swap the current and next values
 		double (*tmp)[dsize[1]] = cur; cur = next; next = tmp;
 	}
-	//*** finally share the loop counter and main field after the main loop body
+	// finally share the loop counter and main field after the main loop body
 	PDI_share("ii", &ii, PDI_OUT);
 	PDI_reclaim("ii");
 	PDI_share("main_field", cur, PDI_OUT);
diff --git a/solutions/ex5.c b/solutions/ex5.c
index d2f753b..2b0c6dc 100644
--- a/solutions/ex5.c
+++ b/solutions/ex5.c
@@ -232,9 +232,9 @@ int main( int argc, char* argv[] )
 		double (*tmp)[dsize[1]] = cur; cur = next; next = tmp;
 	}
 	// finally share the loop counter and main field after the main loop body
-	PDI_share("main_field", cur, PDI_OUT);
-	PDI_share("ii",         &ii, PDI_OUT);
+	PDI_share("ii", &ii, PDI_OUT);
 	PDI_reclaim("ii");
+	PDI_share("main_field", cur, PDI_OUT);
 	PDI_reclaim("main_field");
 	
 	// finalize PDI