Explain FIG1 and FIG2 usage

2 files changed, 39 insertions, 6 deletions

diff --git a/dab.bib b/dab.bib
index f634786..bdfbbdf 100644
--- a/dab.bib
+++ b/dab.bib
@@ -44,15 +44,23 @@ manual{Xarticle,
 
 @manual{etsidab,
     author = {{ETSI}},
-    month = {{June}}, 
-    year = {2006},
-    note = {V1.4.1},
+    month = {{October}},
+    year = {2016},
+    note = {V2.1.1},
     title = {{EN 300 401, Digital Audio Broadcasting (DAB) to mobile, portable and fixed receivers}},
 }
 
+@manual{etsidabtables,
+    author = {{ETSI}},
+    month = {{August}},
+    year = {2017},
+    note = {V2.2.1},
+    title = {{TS 101 768, Digital Audio Broadcasting (DAB); Registered Tables}},
+}
+
 @manual{etsidabaac,
     author = {{ETSI}},
-    month = {{May}}, 
+    month = {{May}},
     year = {2010},
     note = {V1.2.1},
     title = {{TS 102 563, Digital Audio Broadcasting (DAB); Transport of Advanced Audio Coding (AAC) audio}},
@@ -60,14 +68,14 @@ manual{Xarticle,
 
 @manual{etsidabeti,
     author = {{ETSI}},
-    month = {{September}}, 
+    month = {{September}},
     year = {1997},
     title = {{ETS 300 799, Digital Audio Broadcasting (DAB); Distribution interfaces; Ensemble Transport Interface (ETI)}},
 }
 
 @manual{etsits102427,
     author = {{ETSI}},
-    month = {{July}}, 
+    month = {{July}},
     year = {2005},
     note = {V1.1.1},
     title = {{TS 102 427, Digital Audio Broadcasting (DAB); Data Broadcasting -- MPEG-2 TS streaming}},
diff --git a/datafeatures.tex b/datafeatures.tex
index 3a67fa8..7622b46 100644
--- a/datafeatures.tex
+++ b/datafeatures.tex
@@ -1,5 +1,30 @@
 % LICENSE: see LICENCE
 \section{Data Features}
+\subsection{FIG 1 Labels and FIG 2 Extended Labels}
+The specification offers two ways to carry ensemble, service and component
+labels: through FIG 1 and through FIG 2, specified in clauses 5.2.2.2 and 5.2.2.3
+of ETSI EN 300 401~\cite{etsidab}.
+
+Most receivers are only able to show FIG 1 Labels encoded in the Complete EBU
+Latin character set (defined in ETSI TS 101 756 clause
+5.2~\cite{etsidabtables}). Some are able to display Unicode FIG 1 Labels,
+encoded either in UTF-8 or UCS-2, and, as of early 2019, receiver support for
+FIG 2 Extended Labels is practically absent.
+
+The main downside of carrying Unicode FIG 1 Labels is the length limitation: 16
+bytes will only encode eight characters in alphabets that require two bytes per
+character. FIG 2 supports up to 32 bytes labels to alleviate this.
+
+The intention is that new ensembles in countries requiring labels in non-latin
+alphabets transmit only FIG 2 Extended Labels, whereas currently operating
+ensembles keep transmitting FIG 1 Labels. This entices receiver manufacturers to
+support FIG 2 without impacting functionality of receivers currently in use.
+Transmitting both FIG 1 and FIG 2 is discouraged by the specification.
+
+The way FIG 2 is encoded has been redefined, which is why ODR-DabMux supports
+two variants: FIG 2 with character flag being the old variant, and FIG 2 with
+text control that will become the default variant.
+
 \subsection{Announcements}
 The ODR-DabMux multiplexer supports the insertion of FIG 0/18 and FIG 0/19 that
 are used to define and trigger announcements according to ETSI TR 101 496-2