diff --git a/NEWS b/NEWS
index 8c30267bf..a7cb523ec 100644
--- a/NEWS
+++ b/NEWS
@@ -9,6 +9,20 @@ New in spot 2.4.0.dev (not yet released)
     --ms-phi-r=RANGE       (FGa{n}&GFb{n})|((FGa{n-1}|GFb{n-1})&(...))
     --ms-phi-s=RANGE       (FGa{n}|GFb{n})&((FGa{n-1}&GFb{n-1})|(...))
 
+  Library:
+
+  - Rename three methods of spot::scc_info. New names are clearer. The
+    old names have been deprecated.
+
+  Deprecation notices:
+
+  (These functions still work but compilers emit warnings.)
+
+  - spot::scc_info::used_acc(), spot::scc_info::used_acc_of() and
+    spot::scc_info::acc() are deprecated. They have been renamed
+    spot::scc_info::marks(), spot::scc_info::marks_of() and
+    spot::scc_info::acc_sets_of() respectively.
+
 New in spot 2.4 (2017-09-06)
 
   Build:
@@ -285,23 +299,23 @@ New in spot 2.4 (2017-09-06)
     from 9 to 16 colors.  While the first 8 colors are similar, they
     are a bit more saturated now.
 
-  Deprecation notices:
+  deprecation notices:
 
-  (These functions still work but compilers emit warnings.)
+  (these functions still work but compilers emit warnings.)
 
   - spot::decompose_strength() is deprecated, it has been renamed
     to spot::decompose_scc().
 
-  - spot::dtwa_complement() is deprecated.  Prefer the more generic
+  - spot::dtwa_complement() is deprecated.  prefer the more generic
     spot::dualize() instead.
 
-  - The spot::twa::prop_deterministic() methods have been renamed to
+  - the spot::twa::prop_deterministic() methods have been renamed to
     spot::twa::prop_universal() for consistency with the change to
-    is_deterministic() listed above.  We have kept
+    is_deterministic() listed above.  we have kept
     spot::twa::prop_deterministic() as a deprecated synonym for
     spot::twa::prop_universal() to help backward compatibility.
 
-  - The spot::copy() function is deprecated.  Use
+  - the spot::copy() function is deprecated.  use
     spot::make_twa_graph() instead.
 
 New in spot 2.3.5 (2017-06-22)
diff --git a/spot/twaalgos/dtwasat.cc b/spot/twaalgos/dtwasat.cc
index 71a5cd9c1..7a8f87ad5 100644
--- a/spot/twaalgos/dtwasat.cc
+++ b/spot/twaalgos/dtwasat.cc
@@ -400,7 +400,7 @@ namespace spot
       d.is_weak_scc = sm.weak_sccs();
       unsigned scccount = sm.scc_count();
       {
-        auto tmp = sm.used_acc();
+        auto tmp = sm.marks();
         d.scc_marks.reserve(scccount);
         for (auto& v: tmp)
           {
diff --git a/spot/twaalgos/isweakscc.cc b/spot/twaalgos/isweakscc.cc
index 02d22a4f3..5bd292e5e 100644
--- a/spot/twaalgos/isweakscc.cc
+++ b/spot/twaalgos/isweakscc.cc
@@ -74,7 +74,7 @@ namespace spot
     if (map.is_rejecting_scc(scc))
       return true;
     // If all transitions use the same acceptance set, the SCC is weak.
-    return map.used_acc_of(scc).size() == 1;
+    return map.marks_of(scc).size() == 1;
   }
 
   bool
@@ -117,7 +117,7 @@ namespace spot
 
     // If all transitions use all acceptance conditions, the SCC is weak.
     return (map.is_accepting_scc(scc)
-            && map.used_acc_of(scc).size() == 1
+            && map.marks_of(scc).size() == 1
             && is_complete_scc(map, scc));
   }
 }
diff --git a/spot/twaalgos/remfin.cc b/spot/twaalgos/remfin.cc
index a803954ed..fc9a9349d 100644
--- a/spot/twaalgos/remfin.cc
+++ b/spot/twaalgos/remfin.cc
@@ -309,7 +309,7 @@ namespace spot
               // The main copy is only accepting for inf_alone
               // and for all Inf sets that have no matching Fin
               // sets in this SCC.
-              auto scc_pairs = rs_pairs_view(pairs, si.acc(scc));
+              auto scc_pairs = rs_pairs_view(pairs, si.acc_sets_of(scc));
               auto scc_infs_alone = scc_pairs.infs_alone();
 
               for (const auto& e: si.edges_of(scc))
@@ -676,7 +676,7 @@ namespace spot
       std::vector<unsigned> state_map(nst);
       for (unsigned n = 0; n < nscc; ++n)
         {
-          auto m = si.acc(n);
+          auto m = si.acc_sets_of(n);
           auto states = si.states_of(n);
           trace << "SCC #" << n << " uses " << m << '\n';
 
diff --git a/spot/twaalgos/sccfilter.cc b/spot/twaalgos/sccfilter.cc
index 1a354aed8..80b084528 100644
--- a/spot/twaalgos/sccfilter.cc
+++ b/spot/twaalgos/sccfilter.cc
@@ -223,7 +223,7 @@ namespace spot
              "generalized Büchi acceptance");
 
         unsigned scc_count = this->si->scc_count();
-        auto used_acc = this->si->used_acc();
+        auto used_acc = this->si->marks();
         assert(used_acc.size() == scc_count);
         strip_.resize(scc_count);
         std::vector<unsigned> cnt(scc_count); // # of useful sets in each SCC
diff --git a/spot/twaalgos/sccinfo.cc b/spot/twaalgos/sccinfo.cc
index eda86b5b8..54fd09b9c 100644
--- a/spot/twaalgos/sccinfo.cc
+++ b/spot/twaalgos/sccinfo.cc
@@ -318,7 +318,7 @@ namespace spot
   }
 
 
-  std::set<acc_cond::mark_t> scc_info::used_acc_of(unsigned scc) const
+  std::set<acc_cond::mark_t> scc_info::marks_of(unsigned scc) const
   {
     std::set<acc_cond::mark_t> res;
     for (auto& t: inner_edges_of(scc))
@@ -326,7 +326,7 @@ namespace spot
     return res;
   }
 
-  std::vector<std::set<acc_cond::mark_t>> scc_info::used_acc() const
+  std::vector<std::set<acc_cond::mark_t>> scc_info::marks() const
   {
     unsigned n = aut_->num_states();
     std::vector<std::set<acc_cond::mark_t>> result(scc_count());
@@ -351,7 +351,7 @@ namespace spot
   {
     unsigned n = scc_count();
     std::vector<bool> result(scc_count());
-    auto acc = used_acc();
+    auto acc = marks();
     for (unsigned s = 0; s < n; ++s)
       result[s] = is_rejecting_scc(s) || acc[s].size() == 1;
     return result;
@@ -413,7 +413,8 @@ namespace spot
         q.pop();
 
         out << "  " << state << " [shape=box,"
-            << (aut->acc().accepting(m->acc(state)) ? "style=bold," : "")
+            << (aut->acc().accepting(m->acc_sets_of(state)) ?
+                "style=bold," : "")
             << "label=\"" << state;
         {
           size_t n = m->states_of(state).size();
diff --git a/spot/twaalgos/sccinfo.hh b/spot/twaalgos/sccinfo.hh
index 0b2d18e37..91f90ac2f 100644
--- a/spot/twaalgos/sccinfo.hh
+++ b/spot/twaalgos/sccinfo.hh
@@ -476,9 +476,10 @@ namespace spot
       return node(scc).is_trivial();
     }
 
+    SPOT_DEPRECATED("use acc_sets_of() instead")
     acc_cond::mark_t acc(unsigned scc) const
     {
-      return node(scc).acc_marks();
+      return acc_sets_of(scc);
     }
 
     bool is_accepting_scc(unsigned scc) const
@@ -505,20 +506,33 @@ namespace spot
       return reachable_state(st) && node(scc_of(st)).is_useful();
     }
 
-    /// \brief Return the set of all used acceptance combinations, for
-    /// each accepting SCC.
-    std::vector<std::set<acc_cond::mark_t>> used_acc() const;
+    /// \brief Returns, for each accepting SCC, the set of all marks appearing
+    /// in it.
+    std::vector<std::set<acc_cond::mark_t>> marks() const;
+    std::set<acc_cond::mark_t> marks_of(unsigned scc) const;
 
-    std::set<acc_cond::mark_t> used_acc_of(unsigned scc) const;
-
-    /// sets that contain at least one transition of the SCC
-    acc_cond::mark_t acc_sets_of(unsigned scc) const
+    // Same as above, with old names.
+    SPOT_DEPRECATED("use marks() instead")
+    std::vector<std::set<acc_cond::mark_t>> used_acc() const
     {
-      // FIXME: Why do we have two name for this method?
-      return acc(scc);
+      return marks();
+    }
+    SPOT_DEPRECATED("use marks_of() instead")
+    std::set<acc_cond::mark_t> used_acc_of(unsigned scc) const
+    {
+      return marks_of(scc);
     }
 
-    /// sets that contain the entire SCC
+    /// \brief Returns, for a given SCC, the set of all colors appearing in it.
+    /// It is the set of colors that appear in some mark among those returned by
+    /// marks_of().
+    acc_cond::mark_t acc_sets_of(unsigned scc) const
+    {
+      return node(scc).acc_marks();
+    }
+
+    /// Returns, for a given SCC, the set of colors that appear on all of its
+    /// transitions.
     acc_cond::mark_t common_sets_of(unsigned scc) const
     {
       return node(scc).common_marks();