diff --git a/docs/configes sample/in_file_config.json b/docs/configes sample/in_file_config.json
new file mode 100644
index 0000000..15e0802
--- /dev/null
+++ b/docs/configes sample/in_file_config.json	
@@ -0,0 +1,9 @@
+{
+    "Game_threads": {
+        "orbit_demo": {
+            "ship_info": {
+                "mass" : "basic_config:basic_number"
+            }
+        }
+    }
+}
\ No newline at end of file
diff --git a/libs/P_C.py b/libs/P_C.py
index 782ba22..edbd832 100644
--- a/libs/P_C.py
+++ b/libs/P_C.py
@@ -40,7 +40,7 @@ def S_N_M(A, B):  # stand for Scientific notation multiple
 def S_N_D(A, B):  # stand for Scientific notation divided
     """
     formats:
-    A & B list format:docs.basic_config.json:basic_number"""
+    A & B list format:docs.basic_config:basic_number"""
     C = [F_D(A[0], B[0]), F_Mi(A[1], B[1])]
     S_C_float_check(C)
     Unit1, Unit2 = A[2] + B[3], A[3] + B[2]
@@ -49,3 +49,7 @@ def S_N_D(A, B):  # stand for Scientific notation divided
     libs.tools.D_C(Unit1, Unit2)
     C += [Unit1, Unit2]
     return C
+
+
+def G_C(M, m, R): #stand for gravity calculation
+    pass