diff --git a/doc/generators.yaml b/doc/generators.yaml
index 4813dfde..5cf1ac16 100644
--- a/doc/generators.yaml
+++ b/doc/generators.yaml
@@ -176,10 +176,7 @@ data:
       hard_cases_group:
         # Directories may contain a testdata.yaml that will be written as specified.
         testdata.yaml:
-          on_reject: break
-          accept_score: "25"
-          range: 0 25
-          grader_flags: min
+          input_validator_flags: --max_n 1000
 
         # To enable automatic numbering of testcases, data: may also contain a list of
         # single-element dictionaries instead of a single dictionary. In this case,
diff --git a/support/schemas/generators.cue b/support/schemas/generators.cue
index aad46fee..f1489429 100644
--- a/support/schemas/generators.cue
+++ b/support/schemas/generators.cue
@@ -1,6 +1,4 @@
-package problemformat
-
-// cue version 0.6
+// Use cue version 0.6 or later
 // To validate generators.yaml using cue:
 // > cue vet generators.yaml *.cue -d "#Generators"
 
@@ -49,7 +47,7 @@ casepath: =~"^\(filename)(/\(basename))*$"
 #data_list: {[name | ""]: #testgroup | #testcase} & struct.MinFields(1) & struct.MaxFields(1)
 
 #testgroup: {
-	data?: #data_dict | [...#data_list]
+	data?: null |  #data_dict | [...#data_list]
 	include?: [...name]
 	#config
 }
diff --git a/support/schemas/testdata.cue b/support/schemas/testdata.cue
deleted file mode 100644
index 162dd06f..00000000
--- a/support/schemas/testdata.cue
+++ /dev/null
@@ -1,48 +0,0 @@
-package problemformat
-
-import "strings"
-import "strconv"
-
-#filename: =~ "^[a-zA-Z0-9][a-zA-Z0-9_.-]*[a-zA-Z0-9]$"
-#path: =~ "[a-zA-Z0-9_.-/]*"
-
-#testdata_settings: {
-	on_reject: *"break" | "continue"
-	grading: *"default" | "custom"
-	grader_flags:  *"" | string
-    if grading == "default" { grader_flags? : #default_grader_flags }
-	input_alidator_flags: *"" | string
-	output_validator_flags: *"" |string
-	accept_score: *"1" | #score
-	reject_score: *"0" | #score
-	range: *"-inf +inf" | string
-    // Verify that the scores and ranges make sense:
-    _range_syntax: strings.Split(range, " ") & [#score, #score] // space-separated scores
-    _lo: strconv.ParseFloat(strings.Split(range, " ")[0], 64)   // parses to float (including '-inf')
-    _hi: strconv.ParseFloat(strings.Split(range, " ")[1], 64)
-    _wa: strconv.ParseFloat(reject_score, 64)
-    _ac: strconv.ParseFloat(accept_score, 64)
-    _order: true & _lo <= _wa  & _wa <= _ac & _ac <= _hi
-}
-// matches "1", "06", "21", ".4", "-1.2", but not 'inf'
-#score: =~ "^-?([0-9]+|[0-9]*.[0-9]+)$"
-
-// Default grader
-// --------------
-
-#default_grader_flags: this={
-    string
-    _as_struct: { for w in strings.Split(this, " ")  { (w): _ } }  // convert to struct and ...
-    _as_struct: #valid_default_grader_fields                       // ... validate its fields
-    }
-
-// Default grader flags (converted to fields of a CUE struct for validation)
-#valid_default_grader_fields: {
-    #verdict_aggregation_mode?   // at most one verdict aggregation mode
-    #score_aggregation_mode?     // at most one score aggregation mode
-    ignore_sample?: _            // two more optional flags
-    accept_if_any_accepted?: _
-}
-
-#verdict_aggregation_mode: {first_error: _ } | *{worst_error: _  } | {always_accept: _ }
-#score_aggregation_mode:  {min: _ } | {max: _ } | *{sum: _ } | {avg: _ }
diff --git a/test/problems/generatorincludes/generators/generators.yaml b/test/problems/generatorincludes/generators/generators.yaml
index 292c89df..67d1519a 100644
--- a/test/problems/generatorincludes/generators/generators.yaml
+++ b/test/problems/generatorincludes/generators/generators.yaml
@@ -11,8 +11,8 @@ data:
     data:
       - small:
           testdata.yaml:
-            input_validator_flags: --small
-            input_validators:
+            output_validator_flags: space_change_sensitive
+            input_validator_flags:
               connected: --small
               strongly-connected: --small
           data: