fixup: required to

source/compatibility.tex

@@ -2708,7 +2708,7 @@
 \tcode{sizeof(char*)}
 in C.
 \difficulty
-Programs are required to add explicit casts to the appropriate rvalue.
+Programs need to add explicit casts to the appropriate rvalue.
 \howwide
 Rare.
 
@@ -2803,7 +2803,7 @@
 
 \diffref{dcl.typedef}
 \change
-A \Cpp{} \grammarterm{typedef-name} is required to be different from any class type name declared
+A \Cpp{} \grammarterm{typedef-name} needs to be different from any class type name declared
 in the same scope (except if the typedef is a synonym of the class name with the
 same name). In C, a \grammarterm{typedef-name} and a struct tag name declared in the same scope
 can have the same name (because they have different name spaces).
@@ -2836,9 +2836,9 @@
 
 \diffref{dcl.type} [see also \ref{basic.link}]
 \change
-Const objects are required to be initialized in \Cpp{} but can be left uninitialized in C.
+Const objects need to be initialized in \Cpp{} but can be left uninitialized in C.
 \rationale
-A const object cannot be assigned to so it is required to be initialized
+A const object cannot be assigned to so it needs to be initialized
 to hold a useful value.
 \effect
 Deletion of semantically well-defined feature.
@@ -2973,9 +2973,10 @@
 
 \diffref{dcl.init.string}
 \change
-In \Cpp{}, when initializing an array of character with a string, the number of
+In \Cpp{}, when initializing an array of character with a string,
+it is not possible for the number of
 characters in the string (including the terminating \tcode{'\textbackslash 0'})
-is required not to exceed the
+to exceed the
 number of elements in the array. In C, an array can be initialized with a string even if
 the array is not large enough to contain the string-terminating \tcode{'\textbackslash 0'}.