Greek keyboard layout questions

Here I am talking about an additional “Phonetic” Greek keyboard layout (which I make):

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║ § ´ ║ ¤ ¹ ║ @ ² ║ # ³ ║ $ £ ║ % ‰ ║ | ¦ ║ & ≠ ║ < ≤ ║ > ≥ ║ \ ‖ ║ ^ ± ║ ~ ∞ ║ Backspace ║
║ + ` ║ ! 1 ║ : 2 ║ . 3 ║ * 4 ║ _ 5 ║ — 6 ║ = 7 ║ , 8 ║ ; 9 ║ / 0 ║ - − ║ ? ≈ ║           ║
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║ Tab    ║ ʹ •  ║ Ή ← ║ Η → ║ Ο ” ║ Ό ̓  ║ ΅ ¥ ║ Ν Ϗ ║ Κ Ϟ ║ Γ Ͼ ║ Β ϖ ║ Ψ © ║ Φ ⁄ ║  Enter ║
║        ║ · ͵  ║ ή [ ║ η ] ║ ο » ║ ό ́  ║ ¨ € ║ ν ϗ ║ κ ϟ ║ γ ͼ ║ β ϐ ║ ψ ¢ ║ φ ϕ ║        ║
╠════════╩═╦═══╩═╦═══╩═╦═══╩═╦═══╩═╦═══╩═╦═══╩═╦═══╩═╦═══╩═╦═══╩═╦═══╩═╦═══╩═╦═══╩═╗      ║
║ CapsLock ║ Υ ̄  ║ Ε ⟨ ║ Ι ⟩ ║ Α ̈  ║ Ά ˜ ║ Λ Ͽ ║ Ρ ® ║ Τ Ͻ ║ Σ Ϲ ║ Π Ϡ ║ Χ × ║ Ζ ÷ ║      ║
║          ║ υ ' ║ ε ( ║ ι ) ║ α " ║ ά ̃  ║ λ ͽ ║ ρ ϱ ║ τ ͻ ║ σ ϲ ║ π ϡ ║ χ ϰ ║ ζ ° ║      ║
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║ Shift ║ – ‑ ║ Ύ ϓ ║ Έ ̆  ║ Ί ͺ  ║ Ω “ ║ Ώ ̔  ║ Ξ Ϝ ║ Μ Ϻ ║ Δ ◊ ║ Σ Ϛ ║ Θ ϴ ║         Shift ║
║       ║ - … ║ ύ ϒ ║ έ { ║ ί } ║ ω « ║ ώ ̀  ║ ξ ϝ ║ μ ϻ ║ δ ₯ ║ ς ϛ ║ θ ϑ ║               ║
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║ Ctrl    ║ Fn  ║ OS  ║  Alt  ║                              ║ AltGr ║ OS  ║ Mn  ║   Ctrl ║
║         ║     ║     ║       ║                              ║       ║     ║     ║        ║
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The layout is done as an addition to the Lithuanian Ergomonic layout (Ratisė):

╔═════╦═════╦═════╦═════╦═════╦═════╦═════╦═════╦═════╦═════╦═════╦═════╦═════╦═══════════╗
║ § ´ ║ ¤ ¡ ║ @ ← ║ # → ║ $ £ ║ % ‰ ║ | ¦ ║ & ≠ ║ < ≤ ║ > ≥ ║ \ ‖ ║ W ß ║ ~ ¿ ║ Backspace ║
║ + ` ║ ! ’ ║ : ⟨ ║ . ⟩ ║ * ” ║ _ … ║ — ^ ║ = 7 ║ , 8 ║ ; 9 ║ / ÷ ║ w Ω ║ ? ≈ ║           ║
╠═════╩══╦══╩══╦══╩══╦══╩══╦══╩══╦══╩══╦══╩══╦══╩══╦══╩══╦══╩══╦══╩══╦══╩══╦══╩══╦════════╣
║ Tab    ║ Ū › ║ Ė ° ║ Y ˆ ║ O » ║ Q ↑ ║ J ¥ ║ N ¬ ║ K † ║ G • ║ B ∞ ║ C © ║ F ® ║  Enter ║
║        ║ ū ‘ ║ ė [ ║ y ] ║ o “ ║ q ́  ║ j € ║ n 4 ║ k 5 ║ g 6 ║ b × ║ c ¢ ║ f / ║        ║
╠════════╩═╦═══╩═╦═══╩═╦═══╩═╦═══╩═╦═══╩═╦═══╩═╦═══╩═╦═══╩═╦═══╩═╦═══╩═╦═══╩═╦═══╩═╗      ║
║ CapsLock ║ U ¯ ║ E ` ║ I ´ ║ A ¨ ║ H ˜ ║ L Ł ║ R ¹ ║ T ² ║ S ³ ║ P ¶ ║ Ž ¸ ║ Z ® ║      ║
║          ║ u ' ║ e ( ║ i ) ║ a " ║ h ̃  ║ l ł ║ r 1 ║ t 2 ║ s 3 ║ p − ║ ž - ║ z ° ║      ║
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║ Shift ║ – ‑ ║ Ų ‹ ║ Ę ˘ ║ Į ˇ ║ Ą « ║ X ↓ ║ V ◊ ║ M µ ║ D ‡ ║ Š · ║ Č ± ║         Shift ║
║       ║ - ̇  ║ ų ‚ ║ ę { ║ į } ║ ą „ ║ x ̀  ║ v √ ║ m 0 ║ d . ║ š , ║ č + ║               ║
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║ Ctrl    ║ Fn  ║ OS  ║  Alt  ║                              ║ AltGr ║ OS  ║ Mn  ║   Ctrl ║
║         ║     ║     ║       ║                              ║       ║     ║     ║        ║
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Keymap levels:

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║ 2 4 ║
║ 1 3 ║
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1 — First level.
2 — Shifted second level.
3 — AltGr third level.
4 — Shifted AltGr fourth level.

I am appealing to Greek language users for some help, any comments, suggestions on how to better arrange some letters/characters (especially those on the third/forth level of the keyboard) for convenience or better associations for memorizing.

Letters with ‘dialytika’ will be entered through a dead key.

My knowledge of Greek is more or less limited to knowing Greek letters.

I live in Greece and I use the greek layout every day.I think that the current greek layout is perfectly useable and doesn’t need to be changed. But, I still don’t know how to write “Μαιου” on Haiku.

I agree. Most people do not use a phonetic layout. However, you are still free to make one. I wouldn’t expect much feedback on it , though.

This layout is not intended for a native Greek users.

It’s not even that ergonomic (not the purpose of this layout, but ergonomics is a desirable thing).

The layout is intended for Lithuanians who more or less need to write in Greek, and who know the Lithuanian layout mentioned above.

This is the standard purpose of “Phonetic” layouts: the ability to write in different writing systems while learning only one keyboard layout (more or less).

However, it is clear that the standard Greek keyboard layout is “phonetic”: modeled after the English QWERTY.

Frequencies of Greek letters in Greek texts (found online):

Letter Frequency
Α 10.75 %
Τ 7.89 %
Ε 7.37 %
Ο 7.15 %
Ι 6.70 %
Σ 6.67 %
Ν 6.17 %
Ρ 4.12 %
Π 3.95 %
Κ 3.66 %
Μ 3.55 %
Η 3.25 %
Υ 2.94 %
Λ 2.54 %
Ί 2.48 %
Ά 2.33 %
Ό 2.33 %
Έ 2.11 %
Γ 1.62 %
Δ 1.55 %
Ή 1.53 %
Χ 1.26 %
Ω 1.16 %
Θ 1.16 %
Ύ 1.02 %
Β 0.74 %
Φ 0.72 %
Ώ 0.58 %
Ξ 0.42 %
Ζ 0.33 %
Ψ 0.15 %

Some questions:

How often are these letters used in the text:
ϊ ϋ ΐ ΰ

ϊ It seems to be the most common of them.

Maybe give these ϊ ϋ letters separate keys?

How are these ϹϽϾϿ signs used in Greek writing?

From what we are using in French, I’d say that having letters that are used in maths or physics are often sufficient. It’s really to avoid frequent keymap switching. When you need to write longer things like citations or translations, better use keymapswitcher and a full greek layout. In a way or another you will have to learn keys.
The advantage of having a separate keyboard layout for phonetic Greek is that it would be usable by everyone. The only problem is that phonetic similarities are changing depending on language roots and so such layout can be quite difficult to arrange. Though, this being a more general approach, you may find some examples on other systems.

I made some changes. Typing through Dead keys eliminated. It seems to me that I have included almost all the necessary symbols for the Greek language.

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║ § ´ ║ ¤ ¡ ║ @ ² ║ # ³ ║ $ £ ║ % ‰ ║ | ¦ ║ & ≠ ║ < ≤ ║ > ≥ ║ \ ‖ ║ – ¥ ║ ~ ¿ ║ Backspace ║
║ + ` ║ ! ʹ  ║ : ⟨ ║ . ⟩ ║ * · ║ _ … ║ — ^ ║ = 7 ║ , 8 ║ ; 9 ║ / ÷ ║ - € ║ ? ≈ ║           ║
╠═════╩══╦══╩══╦══╩══╦══╩══╦══╩══╦══╩══╦══╩══╦══╩══╦══╩══╦══╩══╦══╩══╦══╩══╦══╩══╦════════╣
║ Tab    ║ Ϋ ϔ ║ Ή ϵ ║ Η  ̌ ║ Ο ” ║ Ό ϴ ║ Ϊ ϒ ║ Ν ϼ ║ Κ ϟ ║ Γ ϗ ║ Β ϐ ║ Ψ Ͻ ║ Φ ϡ ║  Enter ║
║        ║ ϋ ΰ ║ ή [ ║ η ] ║ ο » ║ ό  ́ ║ ϊ ΐ ║ ν 4 ║ κ 5 ║ γ 6 ║ β × ║ ψ ͻ ║ φ ϕ ║        ║
╠════════╩═╦═══╩═╦═══╩═╦═══╩═╦═══╩═╦═══╩═╦═══╩═╦═══╩═╦═══╩═╦═══╩═╦═══╩═╦═══╩═╦═══╩═╗      ║
║ CapsLock ║ Υ ̄  ║ Ε  ̔ ║ Ι  ̓ ║ Α  ̈ ║ Ω  ̑ ║ Λ Ϲ ║ Ρ ϱ ║ Τ ϑ ║ Σ Ϛ ║ Π ϖ ║ Ξ Ͼ ║ Ζ Ͽ ║      ║
║          ║ υ ' ║ ε ( ║ ι ) ║ α " ║ ω  ̃ ║ λ ϲ ║ ρ 1 ║ τ 2 ║ σ 3 ║ π − ║ ξ ͼ ║ ζ ͽ ║      ║
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║ Shift ║ – ‑ ║ Ύ ϓ ║ Έ  ̆ ║ Ί ͺ  ║ Ά “ ║ Ώ ϙ ║ Σ Ϝ ║ Μ ϻ ║ Δ ₯ ║ Χ ϰ ║ Θ ± ║         Shift ║
║       ║ -  ̇ ║ ύ  ͵ ║ έ { ║ ί } ║ ά « ║ ώ  ̀ ║ ς ϝ ║ μ 0 ║ δ . ║ χ , ║ θ + ║               ║
╠═══════╩═╦═══╩═╦═══╩═╦═══╩═══╦═╩═════╩═════╩═════╩═════╩════╦╩═════╩╦════╩╦═════╦════════╣
║ Ctrl    ║ Fn  ║ OS  ║  Alt  ║                              ║ AltGr ║ OS  ║ Mn  ║   Ctrl ║
║         ║     ║     ║       ║                              ║       ║     ║     ║        ║
╚═════════╩═════╩═════╩═══════╩══════════════════════════════╩═══════╩═════╩═════╩════════╝

Added polytonic Greek accents and other necessary diacritics…