Write about symbol ambiguity

Describe symbol ambiguity in printed and handwritten forms.

data/text.moi

@@ -154,7 +154,7 @@ For example, the expression \m {vl hb} encodes the symbol \symbol {vl hb} and
 means “vertical (\m {v}) left (\m {l})  line \symbol {vl} combined with
 horizontal (\m {h}) bottom (\m {b}) line \symbol {hb}”.
 
-\3 {Element combination} {featural_combination}
+\2 {Element combination} {featural_combination}
 
 Symbols system can be constructed either by overlaying the symbol elements or by
 modifying them to connect more fluidly. These modifications allow the symbols to
@@ -216,7 +216,63 @@ Figure \tex_ref {fgr:modifications} shows how modifications work for symbol
     \\draw [->] (r3) -- (all) node [auto=left, midway] \{Shift by curved\};
 }}
 
-\3 {Relations to the existing symbols} {featural_existing}
+\2 {Ambiguity in handwritten form} {featural_ambiguity}
+
+We aim to ensure that the symbols are unambiguous in both printed and
+handwritten forms, making the alphabet robust against the imperfections commonly
+found in handwriting. Additionally, the design allows for non-monospaced
+symbols, indicating that the right and left margins of a symbol are not intended
+to carry any significance.
+
+Figure \tex_ref {fgr:ambiguous_1} shows five symbols constructed out of two
+vertical lines. Symbol (1) may not be distinguishable from symbol (2) or (3) in
+handwritten form, since the only difference is the horizontal distance between
+vertical lines, that is hard to make consistent in handwriting. The same is true
+for the second and the third row: any of symbols (2) and (3) may not be
+distinguishable from any of symbols (4) and (5). Moreover, even in printed form
+symbol (2) and (3), as well as (4) and (5) will look the same if we do not
+preserve left and right margins around symbols as it done in non-monospaced
+fonts.
+
+\figure {fgr:ambiguous_1} {Ambiguous symbols with only vertical elements} {
+\tikz {
+
+    \\tikzset\{n/.style=\{circle, minimum size=0.8cm\}\}
+
+    \tikz_symbol {b=+ p=0,2 z=3 w=0.8 vl vr}
+    \tikz_symbol {b=+ p=-0.5,1 z=3 w=0.8 vl vc}
+    \tikz_symbol {b=+ p=0.5,1 z=3 w=0.8 vc vr}
+    \tikz_symbol {b=+ p=-0.5,0 z=3 w=0.8 vl2}
+    \tikz_symbol {b=+ p=0.5,0 z=3 w=0.8 vr2}
+
+    \\node[n, label=\{left:(1)\}] at (0,2) (n1) \{\};
+    \\node[n, label=\{left:(2)\}] at (-0.5,1) (n2) \{\};
+    \\node[n, label=\{right:(3)\}] at (0.5,1) (n3) \{\};
+    \\node[n, label=\{left:(4)\}] at (-0.5,0) (n4) \{\};
+    \\node[n, label=\{right:(5)\}] at (0.5,0) (n5) \{\};
+}}
+
+The same ambiguity emerges when we mix short and long elements.
+
+\figure {fgr:ambiguous_2} {Ambiguous symbols with short and long elements} {
+\tikz {
+    \tikz_symbol {b=+ p=0,0 z=3 w=0.8 vl hc}
+    \tikz_symbol {b=+ p=1,0 z=3 w=0.8 vc hc}
+    \tikz_symbol {b=+ p=2,0 z=3 w=0.8 vl hc}
+}}
+
+Symbols become unambiguous if we add full-length horizontal line at any height
+of a symbol.
+
+\figure {fgr:unambiguous_1} {Unambiguous} {\tikz {
+    \tikz_symbol {b=+ p=0,0 z=3 w=0.8 vl2 hc}
+    \tikz_symbol {b=+ p=1,0 z=3 w=0.8 vl vc hc}
+    \tikz_symbol {b=+ p=2,0 z=3 w=0.8 vl hc vr}
+    \tikz_symbol {b=+ p=3,0 z=3 w=0.8 hc vc vr}
+    \tikz_symbol {b=+ p=4,0 z=3 w=0.8 hc vr2}
+}}
+
+\2 {Relations to the existing symbols} {featural_existing}
 
 The use of basic geometric forms, common in many existing writing systems,
 facilitates easier learning and reproduction of the symbols.