diff --git a/Printers/include/gambit/Printers/printers/asciiprinter.hpp b/Printers/include/gambit/Printers/printers/asciiprinter.hpp
index 11b4c720a3..d99acd74ac 100644
--- a/Printers/include/gambit/Printers/printers/asciiprinter.hpp
+++ b/Printers/include/gambit/Printers/printers/asciiprinter.hpp
@@ -135,9 +135,13 @@ namespace Gambit
         // write the printer buffer to file
         void dump_buffer(bool force=false);
 
-        // retrieve the name of the main output file (used by auxilliary printers to match the names)
+        // actual on-disk path of the main output file (includes any per-rank suffix)
         std::string get_output_filename();
 
+        // output filename before the per-rank MPI suffix; queried by
+        // auxiliary printers to avoid double-appending the rank.
+        std::string get_base_output_filename();
+
         // retrieve the bufferlength (used by auxilliary printers to match the primary printer)
         int get_bufferlength();
 
@@ -170,9 +174,12 @@ namespace Gambit
         void template_print_vec(std::vector<T> const&, const std::string&, const int, const uint, const ulong);
 
       private:
-        /// Output file
+        /// Output file (on-disk path; includes the per-rank suffix under MPI)
         std::string output_file;
 
+        /// Output filename before the per-rank MPI suffix
+        std::string base_output_file;
+
         /// Info file (describes contents of output file, i.e. contents of columns)
         std::string info_file;
 
@@ -214,8 +221,8 @@ namespace Gambit
         uint mpiSize;
         #endif
 
-        /// Number of digits of precision to use in output columns
-        int precision = 10;
+        /// Number of digits of precision to use in output columns (YAML 'precision', default 10)
+        int precision;
 
         /// Full buffer of output to be printed
         // Key is <int rank, int pointID>; value is a Record (for a single model point)
@@ -234,6 +241,10 @@ namespace Gambit
         std::map<int,std::vector<std::string>> label_record; //the 'int' here is the vertex ID. Could make a typedef to make this safer.
         bool info_file_written = false; // Flag to let us know that the info file has been written
 
+        /// Write a '#'-prefixed shorthand-label header line at the top of
+        /// the data file (YAML 'write_header', default false)
+        bool write_header = false;
+        bool header_written = false;
     };
 
     // Register printer so it can be constructed via inifile instructions
diff --git a/Printers/src/printers/asciiprinter/asciiprinter.cpp b/Printers/src/printers/asciiprinter/asciiprinter.cpp
index 0c11ce5b4d..08e217d9b6 100644
--- a/Printers/src/printers/asciiprinter/asciiprinter.cpp
+++ b/Printers/src/printers/asciiprinter/asciiprinter.cpp
@@ -84,6 +84,11 @@ namespace Gambit
     // Common constructor tasks
     void asciiPrinter::common_constructor(const Options& options)
     {
+      // Pick up the resume flag set by PrinterManager. BasePrinter does not
+      // initialise BaseBasePrinter::resume, so without this any later call
+      // to get_resume() would read uninitialised memory.
+      set_resume(options.getValue<bool>("resume"));
+
       if( this->is_auxilliary_printer() ) // check if this is an auxilliary printer
       {
 
@@ -93,9 +98,10 @@ namespace Gambit
          // Get primary printer (need to cast from BasePrinter type to asciiPrinter)
          asciiPrinter* primary = dynamic_cast<asciiPrinter*>(this->get_primary_printer());
 
-         // Name files based on the primary printer filenames
+         // Use the primary's pre-rank filename, otherwise the MPI block
+         // below would append the rank a second time.
          std::ostringstream f;
-         f << primary->get_output_filename() << "_" << printer_name;
+         f << primary->get_base_output_filename() << "_" << printer_name;
          output_file = Utils::ensure_path_exists(options.getValueOrDef<std::string>(f.str(),"output_file"));
 
          // Match the buffer length to the primary printer, or use a user-supplied option
@@ -120,6 +126,9 @@ namespace Gambit
          bufferlength = options.getValueOrDef<uint>(100,"buffer_length");
       }
 
+      // Snapshot the pre-rank-suffix name for auxiliary printers to query.
+      base_output_file = output_file;
+
       // Name "info" file to match "output" file
       std::ostringstream finfo;
       finfo<< output_file <<"_info";
@@ -144,6 +153,22 @@ namespace Gambit
       info_file = finfo2.str();
       #endif
 
+      // Refuse to overwrite a pre-existing output or info file unless the
+      // user has set 'delete_file_on_restart: true', or we are resuming.
+      bool overwrite_file = options.getValueOrDef<bool>(false,"delete_file_on_restart");
+      for(const std::string& f : {output_file, info_file})
+      {
+        if(Utils::file_exists(f) and not overwrite_file and not get_resume())
+        {
+          std::ostringstream errmsg;
+          errmsg << "Refusing to overwrite pre-existing asciiPrinter output file '"<<f<<"'. Please take one of the following actions:" << std::endl
+                 << "  1. Set 'delete_file_on_restart: true' in the Printer options of your input YAML file to give GAMBIT permission to automatically overwrite this file;" << std::endl
+                 << "  2. Choose a different output filename via the 'output_file' printer option;" << std::endl
+                 << "  3. Manually move or delete the existing file '"<<f<<"'.";
+          printer_error().raise(LOCAL_INFO, errmsg.str());
+        }
+      }
+
       // Erase contents of output_file and info_file if they already exist
       std::ofstream output;
       open_output_file(output, output_file, std::ofstream::trunc);
@@ -158,6 +183,7 @@ namespace Gambit
     asciiPrinter::asciiPrinter(const Options& options, BasePrinter* const primary)
       : BasePrinter(primary,options.getValueOrDef<bool>(false,"auxilliary"))
       , output_file("")
+      , base_output_file("")
       , info_file("")
       , bufferlength(100)
       , global(false)
@@ -166,6 +192,7 @@ namespace Gambit
       , myComm() // attaches to MPI_COMM_WORLD, beware collisions with e.g. scanning algorithms.
       , mpiSize(1)
      #endif
+      , precision(10)
       , lastPointID(nullpoint)
     {
       common_constructor(options);
@@ -173,6 +200,19 @@ namespace Gambit
       // Choose whether or not to print invalid and suspicious point codes
       print_suspicious_point_code = options.getValueOrDef<bool>(true,"print_suspicious_point_code");
       print_invalidation_code = options.getValueOrDef<bool>(true,"print_invalidation_code");
+
+      // Number of digits of precision to use in output columns
+      precision = options.getValueOrDef<int>(10,"precision");
+      if(precision < 0)
+      {
+        std::ostringstream errmsg;
+        errmsg << "Invalid value for asciiPrinter option 'precision': " << precision
+               << ". Must be a non-negative integer (number of digits to use for std::setprecision).";
+        printer_error().raise(LOCAL_INFO, errmsg.str());
+      }
+
+      // Optional '#'-prefixed shorthand-label header line at top of data file.
+      write_header = options.getValueOrDef<bool>(false,"write_header");
     }
 
 
@@ -243,8 +283,9 @@ namespace Gambit
     }
 
     // getters for internal variables
-    std::string asciiPrinter::get_output_filename() { return output_file; }
-    int         asciiPrinter::get_bufferlength()    { return bufferlength; }
+    std::string asciiPrinter::get_output_filename()      { return output_file; }
+    std::string asciiPrinter::get_base_output_filename() { return base_output_file; }
+    int         asciiPrinter::get_bufferlength()         { return bufferlength; }
 
     // add results to printer buffer
     void asciiPrinter::addtobuffer(const std::vector<double>& functor_data, const std::vector<std::string>& functor_labels, const int vID, const int rank, const int pointID)
@@ -453,6 +494,24 @@ namespace Gambit
         printer_error().raise(LOCAL_INFO,errmsg.str());
       }
 
+      // Single column width, shared by the header line and data rows.
+      const int colwidth = precision + 13;
+
+      // Shorthand column name: substring after the last "::" (or the whole
+      // label), with whitespace replaced by '_' and prefixed with the
+      // column number to disambiguate collisions.
+      auto shorthand = [](const std::string& full, int col_index_1based)
+      {
+        std::string suffix;
+        std::size_t pos = full.rfind("::");
+        if(pos != std::string::npos) suffix = full.substr(pos + 2);
+        else suffix = full;
+        for(char& c : suffix) if(c == ' ' || c == '\t') c = '_';
+        std::ostringstream out;
+        out << col_index_1based << "_" << suffix;
+        return out.str();
+      };
+
       // Write the file explaining what is in each column of the output file
       if (info_file_written==false)
       {
@@ -467,7 +526,7 @@ namespace Gambit
         {
           int vID        = it->first;
           int length     = it->second;     // slots reserved in output file for these results
-          
+
           for (int i=0; i<length; i++)
           {
             AP_DBUG( std::cout<<"Column "<<column_index<<": "<<label_record.at(vID)[i]<<std::endl; )
@@ -479,6 +538,32 @@ namespace Gambit
         info_file_written=true;
       }
 
+      // Optional shorthand-label header line. The '#' marks it as a comment
+      // for numpy/pandas/gnuplot. A space prefix (or the '#' for the first
+      // column) is emitted before each label so columns stay whitespace-
+      // separated even when a label is wider than colwidth.
+      if (write_header && !header_written)
+      {
+        AP_DBUG( std::cout << "asciiPrinter: Writing data-file header line..." << std::endl; )
+        my_fstream << "#";
+        int column_index = 1;
+        for (std::map<int,int>::iterator
+          it = lineindexrecord.begin(); it != lineindexrecord.end(); it++)
+        {
+          int vID    = it->first;
+          int length = it->second;
+          for (int i = 0; i < length; i++)
+          {
+            if (column_index > 1) my_fstream << " ";
+            my_fstream << std::setw(colwidth - 1)
+                       << shorthand(label_record.at(vID)[i], column_index);
+            column_index++;
+          }
+        }
+        my_fstream << std::endl;
+        header_written = true;
+      }
+
       // Actual dump of buffer to file
       for (Buffer::iterator
         bufentry = buffer.begin(); bufentry != buffer.end(); /* Will increment in loop */ )
@@ -520,8 +605,8 @@ namespace Gambit
               default_value = stream.str();
             }
 
-            // Print to the fstream!
-            int colwidth = precision + 8;  // Just kind of guessing here; tweak as needed
+            // Print to the fstream. Same field width for numeric values and
+            // 'none'/default placeholders so columns align across rows.
             for (uint j=0;j<length;j++)
             {
               if(j>=results->size())
@@ -532,7 +617,7 @@ namespace Gambit
               else
               {
                 // print an entry from the results vector
-                my_fstream<<std::setw(colwidth+5)<<std::scientific<<(*results)[j];
+                my_fstream<<std::setw(colwidth)<<std::scientific<<(*results)[j];
               }
             }
           }
@@ -559,6 +644,11 @@ namespace Gambit
     // Print metadata info to file
     void asciiPrinter::_print_metadata(map_str_str metadata)
     {
+      // Only rank 0 writes; metadata_file is not rank-suffixed, so writes
+      // from other ranks would interleave. Setup metadata is identical
+      // across ranks, and lastPointID is only used by (unimplemented) resume.
+      if(getRank() != 0) return;
+
       // Open metadata file in append mode
       std::ofstream metadata_fstream;
       open_output_file(metadata_fstream, metadata_file, std::ofstream::app);
diff --git a/yaml_files/spartan.yaml b/yaml_files/spartan.yaml
index 68d8adb713..f65251d8c1 100644
--- a/yaml_files/spartan.yaml
+++ b/yaml_files/spartan.yaml
@@ -68,8 +68,9 @@ Printer:
   # options:
   #   output_file: "results.dat"
   #   buffer_length: 10
+  #   precision: 10
+  #   write_header: true
   #   delete_file_on_restart: true
-  #   print_debug_data: true
 
   # printer: none
 
@@ -423,7 +424,7 @@ KeyValues:
     generator: ranlux48
     seed: -1
 
-  print_timing_data: true
+  print_timing_data: false
 
   print_unitcube: true