Slight reformatting of tape format appendix

doc/latex/CTA_Admin_TapeFormat.tex

 \chapter{Tape Format}
 
-\section{AUL File Format}
+\section{Overview}
 
-CTA uses the same file format as CASTOR: AUL\footnote{CASTOR used several file formats over time, but by 2013, only the
-AUL format was in use.}. This format is described in detail on the
+CTA uses the same AUL file format as CASTOR\footnote{CASTOR used several file formats over time, but by 2013,
+only the AUL format was in use.}. This format is based on
+\href{http://webstore.ansi.org/RecordDetail.aspx?sku=INCITS+27-1987\%5bS2008\%5d}{ANSI INCITS 27-1987}
+and is described in detail on the
 \href{http://it-dep-fio-ds.web.cern.ch/it-dep-fio-ds/Documentation/tapedrive/labels.html}{Tape Labels, ANSI and IBM}
 web page (last updated in 2008).
 
@@ -31,7 +33,7 @@ or End of File (EOF).
 \end{tabular}
 \end{center}
 \end{table}
-Volumes that have just been initialised contain no data records, just a single `header label group'. 
+Volumes that have just been initialised contain no data records, just a single `header label group':
 \begin{table}[h!]
 \caption{AUL prelabeled tape with one HDR1}
 \begin{center}
@@ -43,7 +45,7 @@ Volumes that have just been initialised contain no data records, just a single `
 \end{center}
 \end{table}
 
-\subsection{Volume Label (VOL$n$)}
+\section{Volume Label (VOL$n$)}
 
 The very first label record on a labelled volume is VOL1. If this label is incorrect, you will not advance at all.
 
@@ -90,7 +92,7 @@ The format is shown in Table~\ref{tab:volume_label}. Example for beginning of th
 \end{center}
 \end{table}
 
-\subsection{Header Label (HDR$n$)}
+\section{Header Label (HDR$n$)}
 
 HDR1 and HDR2 are normally found together at the beginning of a dataset.
 
@@ -228,7 +230,7 @@ Example of HDR2 for the first file on the tape:
 \end{center}
 \end{table}
 
-\subsection{User Header Label (UHL$n$)}
+\section{User Header Label (UHL$n$)}
 
 The format for UHL1 is shown in Table~\ref{tab:uhl1_utl1_labels}. Example for the second file on the tape:
 \begin{small}
@@ -273,21 +275,21 @@ The format for UHL1 is shown in Table~\ref{tab:uhl1_utl1_labels}. Example for th
 \end{center}
 \end{table}
 
-\subsection{Data Records}
+\section{Data Records}
 
 After a `header label group', data records follow of any length and in any number. Eventually, an EOF will appear and
 then a `trailer label group' is expected.
 
 The data block size is configurable but in practice a block size of 256 KiB has been used everywhere.
 
-\subsection{End of File (EOF$n$)}
+\section{End of File (EOF$n$)}
 
 EOF1 and EOF2 are normally found together at the end of a dataset.
 
 Note that an End of Volume (EOV$n$) label will appear instead of EOF$n$ if this is the final label group on the volume,
 but the dataset continues on another volume. EOV1 and EOV2 are only expected together and at the end of a volume.
 
-\subsection{User Trailer Label (UTL$n$)}
+\section{User Trailer Label (UTL$n$)}
 
 The format for UTL1 is the same as UHL1 (Table~\ref{tab:uhl1_utl1_labels}).