diff --git a/build/entity_generator.rs b/build/entity_generator.rs
index 6012844..27e9d44 100644
--- a/build/entity_generator.rs
+++ b/build/entity_generator.rs
@@ -674,6 +674,9 @@ fn generate_write_code_pairs_for_write_order(
                     attr(&write_command, "DontWriteIfValueIs")
                 ));
             }
+            if !attr(&write_command, "WriteCondition").is_empty() {
+                predicates.push(attr(&write_command, "WriteCondition"));
+            }
             let code = code(&write_command);
             let expected_type = ExpectedType::get_expected_type(code).unwrap();
             let typ = get_code_pair_type(&expected_type);
diff --git a/examples/src/block_examples.rs b/examples/src/block_examples.rs
new file mode 100644
index 0000000..c1b8414
--- /dev/null
+++ b/examples/src/block_examples.rs
@@ -0,0 +1,50 @@
+use dxf::entities::*;
+use dxf::enums::AcadVersion;
+use dxf::{Block, Drawing, Point};
+
+pub fn all() -> dxf::DxfResult<()> {
+    basic_block_and_insert()?;
+    Ok(())
+}
+
+fn basic_block_and_insert() -> dxf::DxfResult<()> {
+    let mut drawing = Drawing::new();
+    drawing.header.version = AcadVersion::R12; // this example only tested on R12
+
+    //
+    // create a block with a unique name...
+    //
+    let mut block = Block::default();
+    block.name = "my-block-name".to_string();
+
+    //
+    // ...and populate it with entities
+    //
+    block.entities.push(Entity {
+        common: Default::default(),
+        specific: EntityType::Line(Line::new(
+            // line from (0,0) to (1,1)
+            Point::new(0.0, 0.0, 0.0),
+            Point::new(1.0, 1.0, 0.0),
+        )),
+    });
+
+    //
+    // add the block to the drawing
+    //
+    drawing.add_block(block);
+
+    //
+    // add a reference to the block with an `INSERT` entity
+    //
+    let mut insert = Insert::default();
+    insert.name = "my-block-name".to_string(); // use the same name as the block defined above
+    insert.location = Point::new(3.0, 3.0, 0.0); // select the base-point of the insertion
+    drawing.add_entity(Entity {
+        common: Default::default(),
+        specific: EntityType::Insert(insert),
+    }); // the end result is a line from (3,3) to (4,4)
+
+    drawing.save_file("basic_block_and_insert.dxf")?;
+    Ok(())
+}
diff --git a/examples/src/main.rs b/examples/src/main.rs
index 62aa713..5879d59 100644
--- a/examples/src/main.rs
+++ b/examples/src/main.rs
@@ -1,8 +1,10 @@
 extern crate dxf;
 
+mod block_examples;
 mod line_type_examples;
 
 fn main() -> dxf::DxfResult<()> {
+    block_examples::all()?;
     line_type_examples::all()?;
     Ok(())
 }
diff --git a/spec/EntitiesSpec.xml b/spec/EntitiesSpec.xml
index 7413f11..a3b36c1 100644
--- a/spec/EntitiesSpec.xml
+++ b/spec/EntitiesSpec.xml
@@ -486,7 +486,7 @@
     <Field Name="__attributes_and_handles" Code="10" Type="(Attribute, Handle)" DefaultValue="vec![]" AllowMultiples="true" GenerateReader="false" GenerateWriter="false" />
     <WriteOrder>
       <WriteSpecificValue Code="100" Value='&amp;String::from("AcDbBlockReference")' MinVersion="R13" />
-      <WriteSpecificValue Code="66" Value="as_i16(ent.attributes().count() > 0)" />
+      <WriteSpecificValue Code="66" Value="as_i16(ent.attributes().count() > 0)" WriteCondition="ent.attributes().count() > 0" />
       <WriteField Field="name" />
       <WriteField Field="location" />
       <WriteField Field="x_scale_factor" />
diff --git a/src/block.rs b/src/block.rs
index 81e43db..91923d9 100644
--- a/src/block.rs
+++ b/src/block.rs
@@ -206,7 +206,7 @@ impl Block {
         write_handles: bool,
     ) {
         pairs.push(CodePair::new_str(0, "BLOCK"));
-        if write_handles {
+        if write_handles && version >= AcadVersion::R13 {
             pairs.push(CodePair::new_string(5, &self.handle.as_string()));
         }
 
@@ -705,4 +705,49 @@ mod tests {
             _ => panic!("expected a circle"),
         }
     }
+
+    /// Test case derived from https://ezdxf.readthedocs.io/en/stable/dxfinternals/block_management.html
+    #[test]
+    fn write_block_r12_compat() {
+        let mut drawing = Drawing::new();
+        drawing.header.version = AcadVersion::R12;
+        let mut block = Block::default();
+        block.name = "block-name".to_string();
+        block.entities.push(Entity {
+            common: Default::default(),
+            specific: EntityType::Line(Line::new(
+                Point::new(0.0, 0.0, 0.0),
+                Point::new(1.0, 1.0, 0.0),
+            )),
+        });
+        drawing.add_block(block);
+        assert_contains_pairs(
+            &drawing,
+            vec![
+                CodePair::new_str(0, "SECTION"),
+                CodePair::new_str(2, "BLOCKS"),
+                CodePair::new_str(0, "BLOCK"),
+                // no handle
+                CodePair::new_str(8, "0"),          // layer
+                CodePair::new_str(2, "block-name"), // name
+                CodePair::new_i16(70, 0),           // flags
+                CodePair::new_f64(10, 0.0),         // insertion point
+                CodePair::new_f64(20, 0.0),
+                CodePair::new_f64(30, 0.0),
+                CodePair::new_str(3, "block-name"), // name again
+                CodePair::new_str(1, ""),           // x-ref name; empty = external
+                CodePair::new_str(0, "LINE"),       // first entity
+                CodePair::new_str(5, "12"),         // entity handle
+            ],
+        );
+        assert_contains_pairs(
+            &drawing,
+            vec![
+                CodePair::new_str(0, "ENDBLK"),
+                CodePair::new_str(5, "10"), // endblk got handle, original block didn't
+                CodePair::new_str(8, "0"),  // layer
+                CodePair::new_str(0, "ENDSEC"), // end of block
+            ],
+        );
+    }
 }
diff --git a/src/drawing.rs b/src/drawing.rs
index c9e6bf7..650adf1 100644
--- a/src/drawing.rs
+++ b/src/drawing.rs
@@ -666,9 +666,11 @@ impl Drawing {
             None
         }
     }
-    pub(crate) fn add_block_no_handle_set(&mut self, block: Block) -> &Block {
+    pub(crate) fn add_block_no_handle_set(&mut self, mut block: Block) -> &Block {
         self.ensure_layer_is_present_for_block(&block);
         self.ensure_line_type_is_present_for_block(&block);
+        self.ensure_block_record_is_present_for_block(&mut block);
+        self.ensure_block_entity_handles_are_set(&mut block);
         self.__blocks.push(block);
         self.__blocks.last().unwrap()
     }
@@ -826,6 +828,17 @@ impl Drawing {
             self.ensure_line_type_is_present(&ent.common.line_type_name);
         }
     }
+    fn ensure_block_record_is_present_for_block(&mut self, block: &mut Block) {
+        self.add_block_record(BlockRecord {
+            name: String::from(&block.name),
+            ..Default::default()
+        });
+    }
+    fn ensure_block_entity_handles_are_set(&mut self, block: &mut Block) {
+        for ent in &mut block.entities {
+            ent.common.handle = self.next_handle();
+        }
+    }
     fn ensure_line_type_is_present_for_object(&mut self, obj: &Object) {
         if let ObjectType::MLineStyle(ref style) = &obj.specific {
             self.ensure_line_type_is_present(&style.style_name);
@@ -933,13 +946,15 @@ impl Drawing {
         pairs.push(CodePair::new_str(0, "ENDSEC"));
     }
     pub(crate) fn add_objects_pairs(&self, pairs: &mut Vec<CodePair>) {
-        pairs.push(CodePair::new_str(0, "SECTION"));
-        pairs.push(CodePair::new_str(2, "OBJECTS"));
-        for o in &self.__objects {
-            o.add_code_pairs(pairs, self.header.version);
-        }
+        if self.header.version >= AcadVersion::R13 {
+            pairs.push(CodePair::new_str(0, "SECTION"));
+            pairs.push(CodePair::new_str(2, "OBJECTS"));
+            for o in &self.__objects {
+                o.add_code_pairs(pairs, self.header.version);
+            }
 
-        pairs.push(CodePair::new_str(0, "ENDSEC"));
+            pairs.push(CodePair::new_str(0, "ENDSEC"));
+        }
     }
     pub(crate) fn add_thumbnail_pairs(&self, pairs: &mut Vec<CodePair>) -> DxfResult<()> {
         if self.header.version >= AcadVersion::R2000 {
@@ -1227,6 +1242,7 @@ impl Drawing {
 #[cfg(test)]
 mod tests {
     use crate::entities::*;
+    use crate::enums::AcadVersion;
     use crate::helper_functions::tests::*;
     use crate::objects::*;
     use crate::tables::*;
@@ -1315,6 +1331,32 @@ mod tests {
         assert_ne!(Handle(0), layer.handle);
     }
 
+    #[test]
+    fn objects_section_is_not_written_on_r12() {
+        let mut drawing = Drawing::new();
+        drawing.header.version = AcadVersion::R12;
+        assert_not_contains_pairs(
+            &drawing,
+            vec![
+                CodePair::new_str(0, "SECTION"),
+                CodePair::new_str(2, "OBJECTS"),
+            ],
+        );
+    }
+
+    #[test]
+    fn objects_section_is_written_on_r13() {
+        let mut drawing = Drawing::new();
+        drawing.header.version = AcadVersion::R13;
+        assert_contains_pairs(
+            &drawing,
+            vec![
+                CodePair::new_str(0, "SECTION"),
+                CodePair::new_str(2, "OBJECTS"),
+            ],
+        );
+    }
+
     #[test]
     fn block_handle_is_set_during_read_if_not_specified() {
         let drawing = drawing_from_pairs(vec![
diff --git a/src/entity.rs b/src/entity.rs
index c4ab47e..12c93ff 100644
--- a/src/entity.rs
+++ b/src/entity.rs
@@ -1436,7 +1436,9 @@ impl Entity {
         } else {
             "AcDb2dPolyline"
         };
-        pairs.push(CodePair::new_str(100, subclass_marker));
+        if version >= AcadVersion::R13 {
+            pairs.push(CodePair::new_str(100, subclass_marker));
+        }
         if version <= AcadVersion::R13 {
             pairs.push(CodePair::new_i16(66, as_i16(poly.contains_vertices)));
         }
@@ -1496,7 +1498,9 @@ impl Entity {
         } else {
             "AcDb2dVertex"
         };
-        pairs.push(CodePair::new_str(100, subclass_marker));
+        if version >= AcadVersion::R13 {
+            pairs.push(CodePair::new_str(100, subclass_marker));
+        }
         pairs.push(CodePair::new_f64(10, v.location.x));
         pairs.push(CodePair::new_f64(20, v.location.y));
         pairs.push(CodePair::new_f64(30, v.location.z));
@@ -1773,6 +1777,7 @@ mod tests {
     #[test]
     fn write_specific_entity_fields() {
         let mut drawing = Drawing::new();
+        drawing.header.version = AcadVersion::R13;
         let line = Line {
             p1: Point::new(1.1, 2.2, 3.3),
             p2: Point::new(4.4, 5.5, 6.6),
@@ -2393,6 +2398,7 @@ mod tests {
     #[test]
     fn write_2d_polyline() {
         let mut drawing = Drawing::new();
+        drawing.header.version = AcadVersion::R13;
         let mut poly = Polyline::default();
         poly.add_vertex(
             &mut drawing,
@@ -2419,6 +2425,7 @@ mod tests {
             common: Default::default(),
             specific: EntityType::Polyline(poly),
         });
+        // TODO
         assert_contains_pairs(
             &drawing,
             vec![
@@ -2472,6 +2479,7 @@ mod tests {
     #[test]
     fn write_3d_polyline() {
         let mut drawing = Drawing::new();
+        drawing.header.version = AcadVersion::R13;
         let mut poly = Polyline::default();
         poly.add_vertex(
             &mut drawing,
@@ -2775,15 +2783,24 @@ mod tests {
     #[test]
     fn write_insert_no_embedded_attributes() {
         let mut drawing = Drawing::new();
-        let ins = Insert::default();
+        let mut ins = Insert::default();
+        ins.name = "insert-name".to_string();
         let ent = Entity::new(EntityType::Insert(ins));
         drawing.add_entity(ent);
+        assert_not_contains_pairs(
+            &drawing,
+            vec![
+                CodePair::new_i16(66, 0),            // contains no attributes
+                CodePair::new_str(2, "insert-name"), // sentinel to ensure we're reading at the correct location
+            ],
+        );
         assert_not_contains_pairs(&drawing, vec![CodePair::new_str(0, "SEQEND")]);
     }
 
     #[test]
     fn write_insert_with_embedded_attributes() {
         let mut drawing = Drawing::new();
+        drawing.header.version = AcadVersion::R13;
         let mut ins = Insert::default();
         ins.add_attribute(&mut drawing, Attribute::default());
         let ent = Entity::new(EntityType::Insert(ins));
diff --git a/src/helper_functions.rs b/src/helper_functions.rs
index 10b40d1..ca70100 100644
--- a/src/helper_functions.rs
+++ b/src/helper_functions.rs
@@ -626,7 +626,10 @@ pub mod tests {
 
     pub fn assert_contains_pairs(drawing: &Drawing, expected: Vec<CodePair>) {
         let actual = drawing.get_code_pairs().ok().unwrap();
-        println!("checking pairs: {:?}", actual);
+        println!("checking pairs:");
+        for pair in &actual {
+            println!("{:?}", pair);
+        }
         let actual_index = try_find_index(&actual, &expected);
         assert!(actual_index.is_some());
     }
@@ -638,7 +641,10 @@ pub mod tests {
 
     pub fn assert_not_contains_pairs(drawing: &Drawing, not_expected: Vec<CodePair>) {
         let actual = drawing.get_code_pairs().ok().unwrap();
-        println!("checking pairs: {:?}", actual);
+        println!("checking pairs:");
+        for pair in &actual {
+            println!("{:?}", pair);
+        }
         let actual_index = try_find_index(&actual, &not_expected);
         assert!(actual_index.is_none());
     }
diff --git a/src/object.rs b/src/object.rs
index 4f0b97d..61a0497 100644
--- a/src/object.rs
+++ b/src/object.rs
@@ -2016,6 +2016,7 @@ mod tests {
         dict.value_handles
             .insert(String::from("key2"), Handle(0xBBBB));
         let mut drawing = Drawing::new();
+        drawing.header.version = AcadVersion::R13; // OBJECTS section only written on R13+
         drawing.add_object(Object {
             common: Default::default(),
             specific: ObjectType::Dictionary(dict),