diff --git a/programs/Hadrons/AWilson.cc b/programs/Hadrons/AWilson.cc
index f9de0926..ad5cae2a 100644
--- a/programs/Hadrons/AWilson.cc
+++ b/programs/Hadrons/AWilson.cc
@@ -26,18 +26,16 @@ directory.
 *******************************************************************************/
 
 #include <Hadrons/AWilson.hpp>
-#include <Hadrons/Environment.hpp>
 
 using namespace Grid;
-using namespace QCD;
 using namespace Hadrons;
 
 /******************************************************************************
-*                          AWilson implementation                             *
+*                         AWilson implementation                              *
 ******************************************************************************/
 // constructor /////////////////////////////////////////////////////////////////
 AWilson::AWilson(const std::string name)
-: FermionAction(name)
+: Module(name)
 {}
 
 // parse parameters ////////////////////////////////////////////////////////////
@@ -46,12 +44,28 @@ void AWilson::parseParameters(XmlReader &reader, const std::string name)
    read(reader, name, par_);
 }
 
-// create operator /////////////////////////////////////////////////////////////
-void AWilson::create(Environment &env)
+// dependencies/products ///////////////////////////////////////////////////////
+std::vector<std::string> AWilson::getInput(void)
 {
-    auto &U      = *env.getGauge();
+    std::vector<std::string> in = {par_.gauge};
+    
+    return in;
+}
+
+std::vector<std::string> AWilson::getOutput(void)
+{
+    std::vector<std::string> out = {getName()};
+    
+    return out;
+}
+
+// execution ///////////////////////////////////////////////////////////////////
+void AWilson::execute(Environment &env)
+{
+    auto &U      = *env.getGauge(par_.gauge);
     auto &grid   = *env.getGrid();
     auto &gridRb = *env.getRbGrid();
     
-    setFMat(new WilsonFermionR(U, grid, gridRb, par_.mass));
+    env.addFermionMatrix(getName(),
+                         new WilsonFermionR(U, grid, gridRb, par_.mass));
 }
diff --git a/programs/Hadrons/AWilson.hpp b/programs/Hadrons/AWilson.hpp
index aa40b99d..cf21eff3 100644
--- a/programs/Hadrons/AWilson.hpp
+++ b/programs/Hadrons/AWilson.hpp
@@ -29,21 +29,22 @@ directory.
 #define Hadrons_AWilson_hpp_
 
 #include <Hadrons/Global.hpp>
-#include <Hadrons/FermionAction.hpp>
-#include <Hadrons/FermionActionFactory.hpp>
+#include <Hadrons/Module.hpp>
+#include <Hadrons/ModuleFactory.hpp>
 
 BEGIN_HADRONS_NAMESPACE
 
 /******************************************************************************
- *                           Wilson fermions                                  *
+ *                            Wilson quark action                             *
  ******************************************************************************/
-class AWilson: public FermionAction
+class AWilson: public Module
 {
 public:
     class Par: Serializable
     {
     public:
-        GRID_SERIALIZABLE_CLASS_MEMBERS(Par, double, mass);
+        GRID_SERIALIZABLE_CLASS_MEMBERS(Par, std::string, gauge,
+                                             double     , mass);
     };
 public:
     // constructor
@@ -52,13 +53,16 @@ public:
     virtual ~AWilson(void) = default;
     // parse parameters
     virtual void parseParameters(XmlReader &reader, const std::string name);
-    // create operator
-    virtual void create(Environment &env);
+    // dependencies/products
+    virtual std::vector<std::string> getInput(void);
+    virtual std::vector<std::string> getOutput(void);
+    // execution
+    virtual void execute(Environment &env);
 private:
     Par par_;
 };
 
-ACTION_REGISTER(AWilson);
+MODULE_REGISTER(AWilson);
 
 END_HADRONS_NAMESPACE
 
diff --git a/programs/Hadrons/Application.cc b/programs/Hadrons/Application.cc
index 1a24f8b6..d8b0d0da 100644
--- a/programs/Hadrons/Application.cc
+++ b/programs/Hadrons/Application.cc
@@ -39,17 +39,10 @@ using namespace Hadrons;
 Application::Application(const std::string parameterFileName)
 : parameterFileName_(parameterFileName)
 , env_(Environment::getInstance())
-, actionFactory_(FermionActionFactory::getInstance())
 , modFactory_(ModuleFactory::getInstance())
 {
-    LOG(Message) << "Fermion actions available:" << std::endl;
-    auto list = actionFactory_.getBuilderList();
-    for (auto &m: list)
-    {
-        LOG(Message) << "  " << m << std::endl;
-    }
     LOG(Message) << "Modules available:" << std::endl;
-    list = modFactory_.getBuilderList();
+    auto list = modFactory_.getBuilderList();
     for (auto &m: list)
     {
         LOG(Message) << "  " << m << std::endl;
@@ -84,18 +77,6 @@ void Application::parseParameterFile(void)
     
     LOG(Message) << "Reading '" << parameterFileName_ << "'..." << std::endl;
     read(reader, "parameters", par_);
-    push(reader, "actions");
-    push(reader, "action");
-    do
-    {
-        read(reader, "id", id);
-        env_.addFermionAction(actionFactory_.create(id.type, id.name));
-        auto &action = *env_.getFermionAction(id.name);
-        action.parseParameters(reader, "options");
-        action.create(env_);
-    } while (reader.nextElement("action"));
-    pop(reader);
-    pop(reader);
     push(reader, "modules");
     push(reader, "module");
     do
@@ -190,7 +171,6 @@ void Application::configLoop(void)
     {
         LOG(Message) << "Starting measurement for trajectory " << t
                      << std::endl;
-        env_.loadUnitGauge();
         execute(program_);
         env_.freeAll();
     }
@@ -219,8 +199,8 @@ unsigned int Application::execute(const std::vector<std::string> &program)
     }
     for (unsigned int i = 0; i < program.size(); ++i)
     {
-        LOG(Message) << "Measurement step (" << i+1 << "/" << program.size()
-                     << ")" << std::endl;
+        LOG(Message) << "Measurement step " << i+1 << "/" << program.size()
+                     << " (module '" << program[i] << "')" << std::endl;
         (*module_[program[i]])(env_);
         LOG(Message) << "allocated propagators: " << env_.nProp() << std::endl;
         if (env_.nProp() > memPeak)
diff --git a/programs/Hadrons/Application.hpp b/programs/Hadrons/Application.hpp
index a5e0e3c4..de788956 100644
--- a/programs/Hadrons/Application.hpp
+++ b/programs/Hadrons/Application.hpp
@@ -29,7 +29,6 @@ directory.
 #define Hadrons_Application_hpp_
 
 #include <Hadrons/Global.hpp>
-#include <Hadrons/FermionActionFactory.hpp>
 #include <Hadrons/Environment.hpp>
 #include <Hadrons/ModuleFactory.hpp>
 
@@ -90,7 +89,6 @@ private:
     std::string                                     parameterFileName_;
     GlobalPar                                       par_;
     Environment                                     &env_;
-    FermionActionFactory                            &actionFactory_;
     ModuleFactory                                   &modFactory_;
     std::map<std::string, std::unique_ptr<Module>>  module_;
     std::map<std::string, std::string>              associatedModule_;
diff --git a/programs/Hadrons/CMeson.cc b/programs/Hadrons/CMeson.cc
index a6e958f9..eb746061 100644
--- a/programs/Hadrons/CMeson.cc
+++ b/programs/Hadrons/CMeson.cc
@@ -45,7 +45,7 @@ void CMeson::parseParameters(XmlReader &reader, const std::string name)
     read(reader, name, par_);
 }
 
-// dependency relation /////////////////////////////////////////////////////////
+// dependencies/products ///////////////////////////////////////////////////////
 std::vector<std::string> CMeson::getInput(void)
 {
     std::vector<std::string> input = {par_.q1, par_.q2};
diff --git a/programs/Hadrons/CMeson.hpp b/programs/Hadrons/CMeson.hpp
index 5e18cfbf..29620726 100644
--- a/programs/Hadrons/CMeson.hpp
+++ b/programs/Hadrons/CMeson.hpp
@@ -61,7 +61,7 @@ public:
     virtual ~CMeson(void) = default;
     // parse parameters
     virtual void parseParameters(XmlReader &reader, const std::string name);
-    // dependency relation
+    // dependencies/products
     virtual std::vector<std::string> getInput(void);
     virtual std::vector<std::string> getOutput(void);
     // execution
diff --git a/programs/Hadrons/Environment.cc b/programs/Hadrons/Environment.cc
index ebd8d010..c72e1fca 100644
--- a/programs/Hadrons/Environment.cc
+++ b/programs/Hadrons/Environment.cc
@@ -42,8 +42,6 @@ Environment::Environment(void)
         GridDefaultMpi()));
     gridRb4d_.reset(SpaceTimeGrid::makeFourDimRedBlackGrid(grid4d_.get()));
     rng4d_.reset(new GridParallelRNG(grid4d_.get()));
-    gauge_.reset(new LatticeGaugeField(grid4d_.get()));
-    loadUnitGauge();
 }
 
 // dry run /////////////////////////////////////////////////////////////////////
@@ -97,22 +95,22 @@ GridRedBlackCartesian * Environment::getRbGrid(const unsigned int Ls) const
 }
 
 // fermion actions /////////////////////////////////////////////////////////////
-void Environment::addFermionAction(FActionPt action)
+void Environment::addFermionMatrix(const std::string name, FMat *fMat)
 {
-    fAction_[action->getName()] = std::move(action);
+    fMat_[name].reset(fMat);
 }
 
-FermionAction * Environment::getFermionAction(const std::string name) const
+Environment::FMat * Environment::getFermionMatrix(const std::string name) const
 {
     try
     {
-        return fAction_.at(name).get();
+        return fMat_.at(name).get();
     }
     catch(std::out_of_range &)
     {
         try
         {
-            return fAction_.at(solverAction_.at(name)).get();
+            return fMat_.at(solverAction_.at(name)).get();
         }
         catch (std::out_of_range &)
         {
@@ -143,9 +141,9 @@ void Environment::callSolver(const std::string name, LatticeFermion &sol,
 }
 
 // quark propagators ///////////////////////////////////////////////////////////
-void Environment::addProp(const std::string name, const unsigned int Ls)
+void Environment::createProp(const std::string name, const unsigned int Ls)
 {
-    GridCartesian *p4 = grid4d_.get();
+    GridCartesian *g4 = getGrid();
 
     if (propExists(name))
     {
@@ -153,21 +151,21 @@ void Environment::addProp(const std::string name, const unsigned int Ls)
     }
     if (Ls > 1)
     {
-        GridCartesian *p;
+        GridCartesian *g;
         
         try
         {
-            p = grid5d_.at(Ls).get();
+            g = grid5d_.at(Ls).get();
         }
         catch(std::out_of_range &)
         {
-            grid5d_[Ls].reset(SpaceTimeGrid::makeFiveDimGrid(Ls, p4));
-            gridRb5d_[Ls].reset(SpaceTimeGrid::makeFiveDimRedBlackGrid(Ls, p4));
-            p = grid5d_[Ls].get();
+            grid5d_[Ls].reset(SpaceTimeGrid::makeFiveDimGrid(Ls, g4));
+            gridRb5d_[Ls].reset(SpaceTimeGrid::makeFiveDimRedBlackGrid(Ls, g4));
+            g = grid5d_[Ls].get();
         }
         if (!isDryRun())
         {
-            prop_[name].reset(new LatticePropagator(p));
+            prop_[name].reset(new LatticePropagator(g));
         }
         else
         {
@@ -179,7 +177,7 @@ void Environment::addProp(const std::string name, const unsigned int Ls)
     {
         if (!isDryRun())
         {
-            prop_[name].reset(new LatticePropagator(p4));
+            prop_[name].reset(new LatticePropagator(g4));
         }
         else
         {
@@ -269,19 +267,44 @@ unsigned int Environment::nProp(void) const
 }
 
 // gauge configuration /////////////////////////////////////////////////////////
-LatticeGaugeField * Environment::getGauge(void) const
+void Environment::createGauge(const std::string name)
 {
-    return gauge_.get();
+    if (gaugeExists(name))
+    {
+        HADRON_ERROR("gauge field '" + name + "' already exists");
+    }
+    gauge_[name].reset(new LatticeGaugeField(getGrid()));
 }
 
-void Environment::loadUnitGauge(void)
+void Environment::freeGauge(const std::string name)
 {
-    SU3::ColdConfiguration(*rng4d_, *gauge_);
+    if (gaugeExists(name))
+    {
+        gauge_.erase(name);
+    }
+    else
+    {
+        HADRON_ERROR("trying to free unknown gauge field '" + name + "'");
+    }
 }
 
-void Environment::loadRandomGauge(void)
+LatticeGaugeField * Environment::getGauge(const std::string name) const
 {
-    SU3::HotConfiguration(*rng4d_, *gauge_);
+    if (gaugeExists(name))
+    {
+        return gauge_.at(name).get();
+    }
+    else
+    {
+        HADRON_ERROR("gauge field '" + name + "' unknown");
+        
+        return nullptr;
+    }
+}
+
+bool Environment::gaugeExists(const std::string name) const
+{
+    return (gauge_.find(name) != gauge_.end());
 }
 
 // random number generator /////////////////////////////////////////////////////
@@ -300,13 +323,19 @@ void Environment::free(const std::string name)
 {
     if (propExists(name))
     {
-        LOG(Message) << "freeing '" << name << "'" << std::endl;
+        LOG(Message) << "freeing propagator '" << name << "'" << std::endl;
         freeProp(name);
     }
+    else if (gaugeExists(name))
+    {
+        LOG(Message) << "freeing gauge field '" << name << "'" << std::endl;
+        freeGauge(name);
+    }
 }
 
 void Environment::freeAll(void)
 {
     prop_.clear();
     propSize_.clear();
+    gauge_.clear();
 }
diff --git a/programs/Hadrons/Environment.hpp b/programs/Hadrons/Environment.hpp
index 906c5aa1..91f0ec23 100644
--- a/programs/Hadrons/Environment.hpp
+++ b/programs/Hadrons/Environment.hpp
@@ -29,7 +29,6 @@ directory.
 #define Hadrons_Environment_hpp_
 
 #include <Hadrons/Global.hpp>
-#include <Hadrons/FermionAction.hpp>
 
 BEGIN_HADRONS_NAMESPACE
 
@@ -40,12 +39,13 @@ class Environment
 {
     SINGLETON(Environment);
 public:
+    typedef FermionOperator<WilsonImplR>                FMat;
     typedef std::function<void(LatticeFermion &,
                                const LatticeFermion &)> Solver;
     typedef std::unique_ptr<GridCartesian>              GridPt;
     typedef std::unique_ptr<GridRedBlackCartesian>      GridRbPt;
     typedef std::unique_ptr<GridParallelRNG>            RngPt;
-    typedef std::unique_ptr<FermionAction>              FActionPt;
+    typedef std::unique_ptr<FMat>                       FMatPt;
     typedef std::unique_ptr<LatticePropagator>          PropPt;
     typedef std::unique_ptr<LatticeGaugeField>          GaugePt;
 public:
@@ -56,8 +56,8 @@ public:
     GridCartesian *         getGrid(const unsigned int Ls = 1) const;
     GridRedBlackCartesian * getRbGrid(const unsigned int Ls = 1) const;
     // fermion actions
-    void                    addFermionAction(FActionPt action);
-    FermionAction *         getFermionAction(const std::string name) const;
+    void                    addFermionMatrix(const std::string name, FMat *mat);
+    FMat *                  getFermionMatrix(const std::string name) const;
     // solvers
     void                    addSolver(const std::string name, Solver s,
                                       const std::string actionName);
@@ -65,18 +65,19 @@ public:
                                        LatticeFermion &sol,
                                        const LatticeFermion &src) const;
     // quark propagators
-    void                    addProp(const std::string name,
-                                    const unsigned int Ls = 1);
+    void                    createProp(const std::string name,
+                                       const unsigned int Ls = 1);
     void                    freeProp(const std::string name);
     bool                    isProp5d(const std::string name) const;
     unsigned int            getPropLs(const std::string name) const;
     LatticePropagator *     getProp(const std::string name) const;
     bool                    propExists(const std::string name) const;
     unsigned int            nProp(void) const;
-    // gauge configuration
-    LatticeGaugeField *     getGauge(void) const;
-    void                    loadUnitGauge(void);
-    void                    loadRandomGauge(void);
+    // gauge configurations
+    void                    createGauge(const std::string name);
+    void                    freeGauge(const std::string name);
+    LatticeGaugeField *     getGauge(const std::string name) const;
+    bool                    gaugeExists(const std::string name) const;
     // random number generator
     void                    setSeed(const std::vector<int> &seed);
     GridParallelRNG *       get4dRng(void) const;
@@ -90,13 +91,12 @@ private:
     GridRbPt                            gridRb4d_;
     std::map<unsigned int, GridRbPt>    gridRb5d_;
     RngPt                               rng4d_;
-    std::map<std::string, FActionPt>    fAction_;
+    std::map<std::string, FMatPt>       fMat_;
     std::map<std::string, Solver>       solver_;
     std::map<std::string, std::string>  solverAction_;
     std::map<std::string, PropPt>       prop_;
     std::map<std::string, unsigned int> propSize_;
-    GaugePt                             gauge_;
-    
+    std::map<std::string, GaugePt>      gauge_;
 };
 
 END_HADRONS_NAMESPACE
diff --git a/programs/Hadrons/FermionAction.hpp b/programs/Hadrons/FermionAction.hpp
deleted file mode 100644
index f3cd1cf7..00000000
--- a/programs/Hadrons/FermionAction.hpp
+++ /dev/null
@@ -1,83 +0,0 @@
-/*******************************************************************************
-Grid physics library, www.github.com/paboyle/Grid 
-
-Source file: programs/Hadrons/FermionAction.hpp
-
-Copyright (C) 2016
-
-Author: Antonin Portelli <antonin.portelli@me.com>
-
-This program is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-This program is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with this program; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
-
-See the full license in the file "LICENSE" in the top level distribution 
-directory.
-*******************************************************************************/
-
-#ifndef Hadrons_FermionAction_hpp_
-#define Hadrons_FermionAction_hpp_
-
-#include <Hadrons/Global.hpp>
-
-BEGIN_HADRONS_NAMESPACE
-
-// action registration macro
-#define ACTION_REGISTER(action)\
-class action##ActionRegistrar\
-{\
-public:\
-    action##ActionRegistrar(void)\
-    {\
-        FermionActionFactory &actionFac = FermionActionFactory::getInstance();\
-        actionFac.registerBuilder(#action, [&](const std::string name)\
-                                  {\
-                                      return std::unique_ptr<action>(\
-                                          new action(name));\
-                                  });\
-    }\
-};\
-static action##ActionRegistrar action##ActionRegistrarInstance;
-
-/******************************************************************************
- *                             FermionAction                                  *
- ******************************************************************************/
-class Environment;
-
-class FermionAction
-{
-public:
-    typedef FermionOperator<WilsonImplR> FMat;
-    typedef std::unique_ptr<FMat>        FMatPt;
-public:
-    // constructor
-    FermionAction(const std::string name);
-    // destructor
-    virtual ~FermionAction(void) = default;
-    // access
-            std::string  getName(void) const;
-    virtual unsigned int getLs(void) const;
-            void         setFMat(FMat *fMat);
-            FMat *       getFMat(void);
-    // parse parameters
-    virtual void parseParameters(XmlReader &reader, const std::string name) = 0;
-    // create operator
-    virtual void create(Environment &env) = 0;
-private:
-    std::string name_;
-    FMatPt      fMat_;
-};
-
-END_HADRONS_NAMESPACE
-
-#endif // Hadrons_FermionAction_hpp_
diff --git a/programs/Hadrons/FermionAction.cc b/programs/Hadrons/GUnit.cc
similarity index 59%
rename from programs/Hadrons/FermionAction.cc
rename to programs/Hadrons/GUnit.cc
index fdd9530c..ce406612 100644
--- a/programs/Hadrons/FermionAction.cc
+++ b/programs/Hadrons/GUnit.cc
@@ -1,7 +1,7 @@
 /*******************************************************************************
 Grid physics library, www.github.com/paboyle/Grid 
 
-Source file: programs/Hadrons/FermionAction.cc
+Source file: programs/Hadrons/GUnit.cc
 
 Copyright (C) 2016
 
@@ -25,37 +25,41 @@ See the full license in the file "LICENSE" in the top level distribution
 directory.
 *******************************************************************************/
 
-#include <Hadrons/FermionAction.hpp>
+#include <Hadrons/GUnit.hpp>
 
 using namespace Grid;
-using namespace QCD;
 using namespace Hadrons;
 
 /******************************************************************************
- *                      FermionAction implementation                          *
- ******************************************************************************/
+*                            GUnit implementation                             *
+******************************************************************************/
 // constructor /////////////////////////////////////////////////////////////////
-FermionAction::FermionAction(const std::string name)
-: name_(name)
+GUnit::GUnit(const std::string name)
+: Module(name)
 {}
 
-// access //////////////////////////////////////////////////////////////////////
-std::string FermionAction::getName(void) const
+// dependencies/products ///////////////////////////////////////////////////////
+std::vector<std::string> GUnit::getInput(void)
 {
-    return name_;
+    return std::vector<std::string>();
 }
 
-unsigned int FermionAction::getLs(void) const
+std::vector<std::string> GUnit::getOutput(void)
 {
-    return 1;
+    std::vector<std::string> out = {getName()};
+    
+    return out;
 }
 
-void FermionAction::setFMat(FMat *fMat)
+// allocation //////////////////////////////////////////////////////////////////
+void GUnit::allocate(Environment &env)
 {
-    fMat_.reset(fMat);
+    env.createGauge(getName());
+    gauge_ = env.getGauge(getName());
 }
 
-FermionAction::FMat * FermionAction::getFMat(void)
+// execution ///////////////////////////////////////////////////////////////////
+void GUnit::execute(Environment &env)
 {
-    return fMat_.get();
+    SU3::ColdConfiguration(*env.get4dRng(), *gauge_);
 }
diff --git a/programs/Hadrons/FermionActionFactory.hpp b/programs/Hadrons/GUnit.hpp
similarity index 64%
rename from programs/Hadrons/FermionActionFactory.hpp
rename to programs/Hadrons/GUnit.hpp
index d9522c31..21e9a15f 100644
--- a/programs/Hadrons/FermionActionFactory.hpp
+++ b/programs/Hadrons/GUnit.hpp
@@ -1,7 +1,7 @@
 /*******************************************************************************
 Grid physics library, www.github.com/paboyle/Grid 
 
-Source file: programs/Hadrons/FermionActionFactory.hpp
+Source file: programs/Hadrons/GUnit.hpp
 
 Copyright (C) 2016
 
@@ -25,23 +25,38 @@ See the full license in the file "LICENSE" in the top level distribution
 directory.
 *******************************************************************************/
 
-#ifndef Hadrons_FermionActionFactory_hpp_
-#define Hadrons_FermionActionFactory_hpp_
+#ifndef Hadrons_GUnit_hpp_
+#define Hadrons_GUnit_hpp_
 
 #include <Hadrons/Global.hpp>
-#include <Hadrons/Factory.hpp>
-#include <Hadrons/FermionAction.hpp>
+#include <Hadrons/Module.hpp>
+#include <Hadrons/ModuleFactory.hpp>
 
 BEGIN_HADRONS_NAMESPACE
 
 /******************************************************************************
- *                         FermionActionFactory                               *
+ *                              Unit gauge                                    *
  ******************************************************************************/
-class FermionActionFactory: public Factory<FermionAction>
+class GUnit: public Module
 {
-    SINGLETON_DEFCTOR(FermionActionFactory)
+public:
+    // constructor
+    GUnit(const std::string name);
+    // destructor
+    virtual ~GUnit(void) = default;
+    // dependencies/products
+    virtual std::vector<std::string> getInput(void);
+    virtual std::vector<std::string> getOutput(void);
+    // allocation
+    virtual void allocate(Environment &env);
+    // execution
+    virtual void execute(Environment &env);
+private:
+    LatticeGaugeField *gauge_ = nullptr;
 };
 
+MODULE_REGISTER(GUnit);
+
 END_HADRONS_NAMESPACE
 
-#endif // Hadrons_FermionActionFactory_hpp_
+#endif // Hadrons_GUnit_hpp_
diff --git a/programs/Hadrons/MQuark.cc b/programs/Hadrons/MQuark.cc
index 04f9042d..b95493e7 100644
--- a/programs/Hadrons/MQuark.cc
+++ b/programs/Hadrons/MQuark.cc
@@ -39,13 +39,13 @@ MQuark::MQuark(const std::string name)
 : Module(name)
 {}
 
-// parse parameters
+// parse parameters ////////////////////////////////////////////////////////////
 void MQuark::parseParameters(XmlReader &reader, const std::string name)
 {
     read(reader, name, par_);
 }
 
-// dependency relation
+// dependencies/products ///////////////////////////////////////////////////////
 std::vector<std::string> MQuark::getInput(void)
 {
     std::vector<std::string> in = {par_.source, par_.solver};
@@ -63,22 +63,31 @@ std::vector<std::string> MQuark::getOutput(void)
 // setup ///////////////////////////////////////////////////////////////////////
 void MQuark::setup(Environment &env)
 {
-    Ls_ = env.getFermionAction(par_.solver)->getLs();
+    auto dim = env.getFermionMatrix(par_.solver)->Grid()->GlobalDimensions();
+    
+    if (dim.size() == Nd)
+    {
+        Ls_ = 1;
+    }
+    else
+    {
+        Ls_ = dim[0];
+    }
 }
 
 // allocation //////////////////////////////////////////////////////////////////
 void MQuark::allocate(Environment &env)
 {
-    env.addProp(getName());
+    env.createProp(getName());
     quark_ = env.getProp(getName());
     if (Ls_ > 1)
     {
-        env.addProp(getName() + "_5d", Ls_);
+        env.createProp(getName() + "_5d", Ls_);
         quark5d_ = env.getProp(getName() + "_5d");
     }
 }
 
-// execution
+// execution ///////////////////////////////////////////////////////////////////
 void MQuark::execute(Environment &env)
 {
     LatticePropagator *fullSource;
diff --git a/programs/Hadrons/MQuark.hpp b/programs/Hadrons/MQuark.hpp
index 90e5f0e4..5b14d0aa 100644
--- a/programs/Hadrons/MQuark.hpp
+++ b/programs/Hadrons/MQuark.hpp
@@ -53,7 +53,7 @@ public:
     virtual ~MQuark(void) = default;
     // parse parameters
     virtual void parseParameters(XmlReader &reader, const std::string name);
-    // dependency relation
+    // dependencies/products
     virtual std::vector<std::string> getInput(void);
     virtual std::vector<std::string> getOutput(void);
     // setup
diff --git a/programs/Hadrons/MSource.cc b/programs/Hadrons/MSource.cc
index 3897db7c..923d5e94 100644
--- a/programs/Hadrons/MSource.cc
+++ b/programs/Hadrons/MSource.cc
@@ -41,13 +41,13 @@ MSource::MSource(const std::string name)
 : Module(name)
 {}
 
-// parse parameters
+// parse parameters ////////////////////////////////////////////////////////////
 void MSource::parseParameters(XmlReader &reader, const std::string name)
 {
     read(reader, name, par_);
 }
 
-// dependency relation
+// dependencies/products ///////////////////////////////////////////////////////
 std::vector<std::string> MSource::getInput(void)
 {
     return std::vector<std::string>();
@@ -68,7 +68,7 @@ void MSource::allocate(Environment &env)
         // 4D sources
         case Grid::SourceType::point:
         case Grid::SourceType::z2Band:
-            env.addProp(getName());
+            env.createProp(getName());
             src_ = env.getProp(getName());
             break;
         // error
diff --git a/programs/Hadrons/MSource.hpp b/programs/Hadrons/MSource.hpp
index 3bc901ad..490be342 100644
--- a/programs/Hadrons/MSource.hpp
+++ b/programs/Hadrons/MSource.hpp
@@ -84,7 +84,7 @@ public:
     virtual ~MSource(void) = default;
     // parse parameters
     virtual void parseParameters(XmlReader &reader, const std::string name);
-    // dependency relation
+    // dependencies/products
     virtual std::vector<std::string> getInput(void);
     virtual std::vector<std::string> getOutput(void);
     // allocation
diff --git a/programs/Hadrons/Makefile.am b/programs/Hadrons/Makefile.am
index 41da337e..499122ac 100644
--- a/programs/Hadrons/Makefile.am
+++ b/programs/Hadrons/Makefile.am
@@ -3,30 +3,33 @@ AM_LDFLAGS  = -L$(top_builddir)/lib
 
 bin_PROGRAMS = Hadrons
 
-## general sources
+# general sources
 Hadrons_SOURCES =   \
     Application.cc  \
     Environment.cc  \
-    FermionAction.cc\
     Global.cc       \
     Hadrons.cc      \
     Module.cc
 
-## fermion actions
-Hadrons_SOURCES +=  \
-    AWilson.cc
-
-## general modules
+# general modules
 Hadrons_SOURCES +=  \
     MQuark.cc       \
     MSource.cc
 
-## solver modules
+# fermion actions
 Hadrons_SOURCES +=  \
-    SRBPrecCG.cc
+    AWilson.cc
 
-## contraction modules
+# contraction modules
 Hadrons_SOURCES +=  \
     CMeson.cc
 
+# gauge modules
+Hadrons_SOURCES +=  \
+    GUnit.cc
+
+# solver modules
+Hadrons_SOURCES +=  \
+    SRBPrecCG.cc
+
 Hadrons_LDADD   = -lGrid
diff --git a/programs/Hadrons/Module.hpp b/programs/Hadrons/Module.hpp
index 4153e77b..1f529944 100644
--- a/programs/Hadrons/Module.hpp
+++ b/programs/Hadrons/Module.hpp
@@ -62,8 +62,8 @@ public:
     // access
     std::string getName(void) const;
     // parse parameters
-    virtual void parseParameters(XmlReader &reader, const std::string name) = 0;
-    // dependency relation
+    virtual void parseParameters(XmlReader &reader, const std::string name) {};
+    // dependencies/products
     virtual std::vector<std::string> getInput(void) = 0;
     virtual std::vector<std::string> getOutput(void) = 0;
     // setup
diff --git a/programs/Hadrons/SRBPrecCG.cc b/programs/Hadrons/SRBPrecCG.cc
index ff4a50d5..42ee332f 100644
--- a/programs/Hadrons/SRBPrecCG.cc
+++ b/programs/Hadrons/SRBPrecCG.cc
@@ -39,16 +39,18 @@ SRBPrecCG::SRBPrecCG(const std::string name)
 : Module(name)
 {}
 
-// parse parameters
+// parse parameters ////////////////////////////////////////////////////////////
 void SRBPrecCG::parseParameters(XmlReader &reader, const std::string name)
 {
    read(reader, name, par_);
 }
 
-// dependency relation
+// dependencies/products ///////////////////////////////////////////////////////
 std::vector<std::string> SRBPrecCG::getInput(void)
 {
-    return std::vector<std::string>();
+    std::vector<std::string> in = {par_.action};
+    
+    return in;
 }
 
 std::vector<std::string> SRBPrecCG::getOutput(void)
@@ -61,7 +63,7 @@ std::vector<std::string> SRBPrecCG::getOutput(void)
 // execution ///////////////////////////////////////////////////////////////////
 void SRBPrecCG::execute(Environment &env)
 {
-    auto &mat   = *(env.getFermionAction(par_.action)->getFMat());
+    auto &mat   = *(env.getFermionMatrix(par_.action));
     auto solver = [&mat, this](LatticeFermion &sol,
                                const LatticeFermion &source)
     {
diff --git a/programs/Hadrons/SRBPrecCG.hpp b/programs/Hadrons/SRBPrecCG.hpp
index 1b072c37..f657bd50 100644
--- a/programs/Hadrons/SRBPrecCG.hpp
+++ b/programs/Hadrons/SRBPrecCG.hpp
@@ -35,7 +35,7 @@ directory.
 BEGIN_HADRONS_NAMESPACE
 
 /******************************************************************************
- *                         SRBPrecCG                                 *
+ *                     Schur red-black preconditioned CG                      *
  ******************************************************************************/
 class SRBPrecCG: public Module
 {
@@ -53,7 +53,7 @@ public:
     virtual ~SRBPrecCG(void) = default;
     // parse parameters
     virtual void parseParameters(XmlReader &reader, const std::string name);
-    // dependency relation
+    // dependencies/products
     virtual std::vector<std::string> getInput(void);
     virtual std::vector<std::string> getOutput(void);
     // execution