diff --git a/lvspec.cls b/lvspec.cls
index 23c8178..3307db4 100644
--- a/lvspec.cls
+++ b/lvspec.cls
@@ -20,6 +20,8 @@
 % base class, defaulting to 10pt
 \LoadClass[10pt]{scrreprt}
 
+\RequirePackage{xparse}
+
 \RequirePackage[top=4.5cm,bottom=5cm,width=\textwidth]{geometry}
 \RequirePackage{makeidx}
 \RequirePackage{minitoc}
diff --git a/raterspec.cls b/raterspec.cls
index 7a6c9fa..4edbf27 100644
--- a/raterspec.cls
+++ b/raterspec.cls
@@ -69,19 +69,28 @@
 % The host environment is the same for all new systems
 %
 
-\def\@raterspec@input@types{
-  \PackageWarning{raterspec}{Missing program-specific input parameter types!
-    \MessageBreak Define using \protect\inputtypes}
-  \todo{No input parameter types have been defined.}
+\let\@@madespec0
+
+\def\@raterspec@mkhook#1#2#3#4{
+  \expandafter\gdef\csname @raterspec@#1\endcsname{
+    \PackageWarning{raterspec}{Missing #2!
+      \MessageBreak Define using \expandafter\protect\csname#1\endcsname}%
+    \todo{No #2 have been defined.}%
+  }%
+  \expandafter\gdef\csname#1\endcsname##1{%
+    \expandafter\gdef\csname @raterspec@#1\endcsname{%
+      #3\input{##1}#4%
+    }%
+  }%
 }
 
-\def\@raterspec@input@params{
-  \PackageWarning{raterspec}{Missing input parameters!
-    \MessageBreak Define using \protect\inputparams}
-  \todo{No input parameters have been defined.}
-}
+\def\makespec{
+  \ifx\@@madespec1%
+    \PackageError{raterspec}{Duplicate call to \protect\makespec}
+  \fi
+
+  \global\let\@@madespec1
 
-\def\@lvspec@posttitle{
   \pnumoff\part{General System}\pnumon
 
   \chapter{Host Environment}
@@ -95,36 +104,38 @@
       \section{Program-Specific Parameter Types}
       \sectiondept{it/uw}
 
-      \@raterspec@input@types
+      \@raterspec@inputtypes
     \index{input data|)}
 
   \chapter{Input Parameters}
     \index{input data!parameters|(}
     \index{parameter|(}
       \input{raterspec/sec/params}
-      \@raterspec@input@params
+      \@raterspec@inputparams
 
     \index{input data!parameters|)}
     \index{parameter|)}
 }
 
 
-\def\inputtypes#1{
-  \gdef\@raterspec@input@types{
+\@raterspec@mkhook{inputtypes}{input types}
+  {%
     % can't really include a sigline here because approvial would be global
     \pnumoff
       Parameter types in this section are common to the \@title@short\ program.
     \pnumon
     \index{parameter type|(}
-      \input{#1}
-    \index{parameter type|)}
   }
-}
+  {\index{parameter type|)}}
 
-\def\inputparams#1{
-  \gdef\@raterspec@input@params{
-    \input{#1}
-  }
+\@raterspec@mkhook{inputparams}{input parameters}
+  {}
+  {}
+
+\AtEndDocument{
+  \ifx\@@madespec0
+    \PackageError{raterspec}{\protect\makespec\space was not called}
+  \fi
 }
 
 
diff --git a/raterspec/param.sty b/raterspec/param.sty
index 7065cd4..9857a78 100644
--- a/raterspec/param.sty
+++ b/raterspec/param.sty
@@ -24,6 +24,11 @@
     \edef\@root{\@ptype@root#1<||}%
     \edef\@type{\@ptype@type#1<#1>||}%
     \expandafter\gdef\csname ptype@#2\endcsname{#3}%
+    % place definition into aux file; will be available next pass
+    \protected@write\@auxout{}{%
+      \string\expandafter\string\gdef
+      \string\csname\space ptype@#2\string\endcsname{#3}%
+    }%
     % typeset definition with link
     \item[%
       \hypertarget{@ptype:#2}{#2}%
@@ -35,7 +40,7 @@
     % ensure that the parent type actually exists
     \ifx\@root\@coreptype\else%
       \expandafter\ifx\csname ptype@\@type\endcsname\relax%
-        \errmessage{unknown parent param type `\@type' for `#2'}
+        \PackageWarning{raterspec}{unknown parent param type `\@type' for `#2'}
       \fi%
     \fi%
     % process any keywords
@@ -76,6 +81,13 @@
   % define constant
   \expandafter\gdef\csname const@#2\endcsname{#1}%
   \expandafter\gdef\csname const@value@#2\endcsname{#3}%
+  % place definition into aux file; will be available next pass
+  \protected@write\@auxout{}{%
+    \string\expandafter\string\gdef
+    \string\csname\space const@#2\string\endcsname{#1}%
+    \string\expandafter\string\gdef
+    \string\csname\space constvalue@#2\string\endcsname{#3}%
+  }%
   % typeset
   \index{constant!{\tt#2}}%
   {\tt\hypertarget{@const:#2}{#2}} & $#3$ & #1 \\
@@ -99,7 +111,7 @@
 \def\unionv#1{%
   % does this type exist?
   \expandafter\ifx\csname ptype@#1\endcsname\relax%
-    \errmessage{unknown param type `#1' for union}
+  \PackageWarning{raterspec}{unknown param type `#1' for union}
   \fi%
   \item{\typeref{#1}}
 }
@@ -152,7 +164,7 @@
 \def\@type@exists@err#1{{%
   \expandafter\let\expandafter\@chk\csname ptype@#1\endcsname
   \ifx\@chk\relax
-    \errmessage{parameter `#1' is undefined}%
+  \PackageWarning{raterspec}{parameter `#1' is undefined}%
   \fi
 }}
 \def\@const@exists@err#1{{%
@@ -160,7 +172,7 @@
   \@ifnumeric{#1}\else
     \expandafter\let\expandafter\@chk\csname const@#1\endcsname
     \ifx\@chk\relax
-      \errmessage{constant `#1' is undefined}%
+      \PackageWarning{raterspec}{constant `#1' is undefined}%
     \fi
   \fi
 }}
@@ -197,10 +209,15 @@
     \edef\@root{\@ptype@root#1<||}%
     \edef\@type{\@ptype@type#1<#1>||}%
     \expandafter\gdef\csname param@#2\endcsname{#3}%
+    % place definition into aux file; will be available next pass
+    \protected@write\@auxout{}{%
+      \string\expandafter\string\gdef
+      \string\csname\space param@#2\string\endcsname{#3}%
+    }%
     % does the given type exist (note that this check assumes that the typedef
     % appears before the param in the specs, as is currently the case)
     \expandafter\ifx\csname ptype@\@type\endcsname\relax%
-      \errmessage{unknown param type: \@type}
+      \PackageWarning{raterspec}{unknown param type: \@type}
     \fi%
     % typeset definition with link
     \item[%
@@ -240,7 +257,7 @@
   \endlinechar-1\relax
   \expandafter\let\expandafter\@@chk\csname param@#1\endcsname
   \ifx\@@chk\relax
-    \PackageError{dwspec}{unknown param: #1}
+    \PackageWarning{raterspec}{unknown param: #1}
   \fi
   \index{parameter!#1@\texttt{#1}}%
   \hyperlink{@param:#1}%
@@ -252,7 +269,7 @@
 \def\paramrefd#1{%
   \expandafter\let\expandafter\@@pchk\csname param@#1\endcsname
   \ifx\@@pchk\empty
-    \PackageError{dwspec}{Unknown parameter: #1}%
+    \PackageWarning{raterspec}{Unknown parameter: #1}%
   \else
     % output
     \@@pchk
diff --git a/raterspec/sec/input.tex b/raterspec/sec/input.tex
index 52a1510..59d2cce 100644
--- a/raterspec/sec/input.tex
+++ b/raterspec/sec/input.tex
@@ -76,6 +76,7 @@ parameter types}.
 
   \typedef core int:
   Any signed 32-bit integer
+
 \end{description}
 
 \index{parameter type|)}