diff --git a/src/fot/entity.rs b/src/fot/entity.rs
index 40c34d9..235c9e4 100644
--- a/src/fot/entity.rs
+++ b/src/fot/entity.rs
@@ -62,7 +62,7 @@ impl DecoderCtx<&mut EntityList, &EntityList> for Entity {
                 wd.write_u16(self.type_idx as u16)?;
                 match self.esh.as_ref() {
                     Some(esh) => wd.write(esh)?,
-                    None => ()
+                    None => (),
                 }
             }
         }
diff --git a/src/fot/entitylist.rs b/src/fot/entitylist.rs
index 3bc3794..8f00b10 100644
--- a/src/fot/entitylist.rs
+++ b/src/fot/entitylist.rs
@@ -4,16 +4,21 @@ use super::esh::ESH;
 use super::fstring::FString;
 use super::raw::Raw;
 use super::stream::{ReadStream, WriteStream};
-use super::tag::Tag;
+use super::tag::{CTag, Tag};
 use anyhow::anyhow;
 use anyhow::Result;
 
-#[derive(Clone, Copy)]
+#[derive(Clone, Copy, PartialEq)]
 pub enum EntityEncoding {
     File,
     World,
 }
 
+const DEFAULT_ENTITY_TAG: CTag<'static> = CTag {
+    name: "<entity>",
+    version: "2",
+};
+
 pub struct EntityList {
     encoding: EntityEncoding,
     entity_file_tag: Option<Tag>,
@@ -22,7 +27,7 @@ pub struct EntityList {
     enc_size: usize,
 
     pub types: Vec<FString>,
-    pub entities: Vec<Entity>
+    pub entities: Vec<Entity>,
 }
 
 impl EntityList {
@@ -42,16 +47,23 @@ impl EntityList {
     pub fn add_or_get_type(&mut self, type_name: FString) -> usize {
         match self.types.iter().position(|f| f.eq(&type_name)) {
             Some(idx) => idx,
-            None => self.add_new_type(type_name)
+            None => self.add_new_type(type_name),
         }
     }
 
     pub fn get_type_name(&self, type_idx: usize) -> &FString {
         &self.types[type_idx]
     }
+
+    pub fn convert(&mut self, new: EntityEncoding) {
+        use EntityEncoding as EE;
+        if self.encoding == EE::World && new == EE::File {
+            self.entity_tag = Some(DEFAULT_ENTITY_TAG.to_tag());
+        }
+    }
 }
 
-impl DecoderCtx<EntityEncoding,EntityEncoding> for EntityList {
+impl DecoderCtx<EntityEncoding, EntityEncoding> for EntityList {
     fn decode(raw: &Raw, offset: usize, size: usize, ctx: EntityEncoding) -> Result<Self> {
         let mut rd = ReadStream::new(raw, offset);
         let mut ent_list = EntityList {
@@ -61,7 +73,7 @@ impl DecoderCtx<EntityEncoding,EntityEncoding> for EntityList {
             unk1: 0,
             enc_size: 0,
             types: Vec::new(),
-            entities: Vec::new()
+            entities: Vec::new(),
         };
 
         Ok(match ctx {
@@ -77,10 +89,10 @@ impl DecoderCtx<EntityEncoding,EntityEncoding> for EntityList {
                     let ent: Entity = rd.read_opt(0, &mut ent_list)?;
                     ent_list.entities.push(ent);
                 }
-                
+
                 ent_list.enc_size = rd.offset() - offset;
                 ent_list
-            },
+            }
 
             EntityEncoding::World => {
                 ent_list.entity_file_tag = Some(rd.read(0)?);
@@ -110,7 +122,7 @@ impl DecoderCtx<EntityEncoding,EntityEncoding> for EntityList {
                     wd.write(self.get_entity_tag())?;
                     wd.write_opt(ent, &self)?;
                 }
-            },
+            }
             EntityEncoding::World => {
                 wd.write(self.entity_file_tag.as_ref().unwrap())?;
                 wd.write_u32(self.types.len() as u32)?;
diff --git a/src/fot/stream.rs b/src/fot/stream.rs
index 4064fac..07a9908 100644
--- a/src/fot/stream.rs
+++ b/src/fot/stream.rs
@@ -46,7 +46,11 @@ impl<'a> ReadStream<'a> {
 
     // read_opt - decode with optional paramters. required for complex structure
     // with different origins (save / entfile) like entities
-    pub fn read_opt<T: DecoderCtx<DCtx, ECtx>, DCtx, ECtx>(&mut self, size: usize, ctx: DCtx) -> Result<T> {
+    pub fn read_opt<T: DecoderCtx<DCtx, ECtx>, DCtx, ECtx>(
+        &mut self,
+        size: usize,
+        ctx: DCtx,
+    ) -> Result<T> {
         let val = T::decode(&self.raw, self.offset(), size, ctx)?;
         self.skip(val.get_enc_size());
         Ok(val)
@@ -112,7 +116,11 @@ impl WriteStream {
         self.buf.get_mut().extend(bytes.iter());
     }
 
-    pub fn write_opt<T: DecoderCtx<DCtx, ECtx>, DCtx, ECtx>(&mut self, val: &T, ctx: ECtx) -> Result<()> {
+    pub fn write_opt<T: DecoderCtx<DCtx, ECtx>, DCtx, ECtx>(
+        &mut self,
+        val: &T,
+        ctx: ECtx,
+    ) -> Result<()> {
         let mut raw = val.encode(ctx)?;
         self.skip(raw.mem.len());
         self.buf.get_mut().append(&mut raw.mem);
diff --git a/src/fot/tag.rs b/src/fot/tag.rs
index b21e66f..b939f68 100644
--- a/src/fot/tag.rs
+++ b/src/fot/tag.rs
@@ -28,3 +28,18 @@ impl Decoder for Tag {
         self.name.get_enc_size() + self.version.get_enc_size()
     }
 }
+
+// struct for Tag consts
+pub struct CTag<'a> {
+    pub name: &'a str,
+    pub version: &'a str,
+}
+
+impl<'a> CTag<'a> {
+    pub fn to_tag(&self) -> Tag {
+        Tag {
+            name: self.name.to_string(),
+            version: self.version.to_string(),
+        }
+    }
+}
diff --git a/src/fot/world.rs b/src/fot/world.rs
index 6e0e705..1552d97 100644
--- a/src/fot/world.rs
+++ b/src/fot/world.rs
@@ -1,6 +1,6 @@
 use super::decoder::{Decoder, DecoderCtx};
+use super::entitylist::{EntityEncoding, EntityList};
 use super::fstring::FString;
-use super::entitylist::{EntityList, EntityEncoding};
 use super::raw::Raw;
 use super::sgd::SGD;
 use super::ssg::SSG;
@@ -25,7 +25,7 @@ pub struct World {
     pub sgd: SGD,
     pub ssg: SSG,
 
-    pub ents: EntityList
+    pub ents: EntityList,
 }
 
 impl World {
@@ -37,7 +37,7 @@ impl World {
         let raw1 = Raw {
             offset: 0,
             size: self.ents.get_enc_size(),
-            mem: self.data.mem[entfile_start..entfile_start+self.ents.get_enc_size()].to_vec()
+            mem: self.data.mem[entfile_start..entfile_start + self.ents.get_enc_size()].to_vec(),
         };
         raw1.dump(Path::new("entfile1.bin"))?;
 
@@ -79,7 +79,7 @@ impl Decoder for World {
             mission,
             sgd,
             ssg,
-            ents
+            ents,
         })
     }