diff --git a/src/error.rs b/src/error.rs
index 0ad4707..2bd721a 100644
--- a/src/error.rs
+++ b/src/error.rs
@@ -3,4 +3,5 @@ use nom;
 #[derive(Debug, PartialEq)]
 pub enum IMFError<'a> {
     Segment(nom::Err<nom::error::Error<&'a [u8]>>),
+    ExtractFields(nom::Err<nom::error::Error<&'a str>>),
 }
diff --git a/src/fragments/mod.rs b/src/fragments/mod.rs
index 0d773c1..3724153 100644
--- a/src/fragments/mod.rs
+++ b/src/fragments/mod.rs
@@ -2,7 +2,7 @@
 pub mod model;
 
 // Generic
-mod whitespace;
+pub mod whitespace;
 mod words;
 mod quoted;
 mod misc_token;
diff --git a/src/multipass/extract_fields.rs b/src/multipass/extract_fields.rs
index e69de29..7bcb585 100644
--- a/src/multipass/extract_fields.rs
+++ b/src/multipass/extract_fields.rs
@@ -0,0 +1,45 @@
+use std::borrow::Cow;
+use nom::{
+    IResult,
+    character::complete::space1,
+    bytes::complete::is_not,
+    combinator::{all_consuming, recognize},
+    multi::{fold_many0, many0, many1},
+    sequence::{pair, tuple},
+};
+
+use crate::multipass::guess_charset::GuessCharset;
+use crate::error::IMFError;
+use crate::fragments::whitespace;
+
+#[derive(Debug, PartialEq)]
+pub struct ExtractFields<'a> {
+    pub raw_header: Cow<'a, str>,
+    pub fields: Vec<&'a str>,
+    pub body: &'a [u8],
+}
+
+impl<'a> TryFrom<GuessCharset<'a>> for ExtractFields<'a> {
+    type Error = IMFError<'a>;
+
+    fn try_from(gcha: GuessCharset<'a>) -> Result<Self, Self::Error> {
+        let mut ef = ExtractFields { fields: vec![], raw_header: gcha.header, body: gcha.body };
+        let (_, fields) = all_consuming(many0(foldable_line))(ef.raw_header).map_err(|e| IMFError::ExtractFields(e))?;
+        panic!();
+        //ef.fields = fields;
+        //Ok(ef)
+    }
+}
+
+/// ```abnf
+/// fold_line = !crlf *(1*(crlf WS) !crlf) crlf
+/// ```
+fn foldable_line<'a>(input: Cow<'a, str>) -> IResult<Cow<'a, str>, Cow<'a, str>> {
+    recognize(tuple((
+        is_not("\r\n"), 
+        many0(pair(
+                many1(pair(whitespace::perm_crlf, space1)), 
+                is_not("\r\n"))), 
+        whitespace::perm_crlf
+    )))(input)
+}
diff --git a/src/multipass/mod.rs b/src/multipass/mod.rs
index e3fa3b1..7d24bda 100644
--- a/src/multipass/mod.rs
+++ b/src/multipass/mod.rs
@@ -1,2 +1,3 @@
 pub mod segment;
 pub mod guess_charset;
+pub mod extract_fields;