Make pointer to metadata object optional

Signed-off-by: Matthias Beyer <mail@beyermatthias.de>

1 files changed, 16 insertions, 1 deletions

diff --git a/doc/paper/main.tex b/doc/paper/main.tex
index bc89d56..9f3cdad 100644
--- a/doc/paper/main.tex
+++ b/doc/paper/main.tex
@@ -121,11 +121,26 @@ Thus, it should only hold the following elements:
 \begin{itemize}
     \item A version number, which describes the version of the format used
     \item A list of pointers to parent blocks
-    \item A pointer to a metadata Block
+    \item An (optional) pointer to a metadata Block
 \end{itemize}
 
 A block may hold more than one pointer to a parent block to make merges possible
 on the block-level.
+
+A block that references more than one parent should not contain any pointer to a
+metadata object.
+If a "merge block" would point to metadata, complexity would be increased
+unecessarily\footnotemark[1].
+
+\footnotetext[1]{
+    A possible optimization would be that merge-blocks are defined in a way that
+    two nodes can always generate the byte-exact same merge block.
+    This would result in the possibility of two devices that do not know
+    eachother to merge two branches of a chain with the exact same merge block
+    object.
+    Encoding metadata like a timestamp in the "Block" type would prevent that.
+}
+
 \ref{pic:blockchain} describes a minimal chain of blocks.
 Each block, save $A$, points to its predecessor.
 $D$ points both to $B$ and $C$, because it merges these blocks, that were both