While serious readers here want to learn to read “condensed” icon inscriptions, technically called “Vyaz'” or “joined/linked” inscriptions, some also want to learn to write it as a calligraphic form.
This page show the letters of Church Slavic in a “pen” form, with wide vertical strokes and thin horizontal and angular strokes.
Vyaz’ inscriptions vary widely. One can make the vertical strokes very long and narrow, which enables more letters in a smaller space, or one may make them shorter. One may make the letters very simple (like the basic forms shown above), or one can make them as ornate as desired, with lots of little added flourishes. And of course they can be written in various colors, red being a common choice for icons.
In combining letters, some vertical strokes in a letter may be shortened to allow the insertion of another letter written small. We see that in the following incription. I will transliterate it with the small letters within and above the inscription in lower case. Omitted letters are in brackets.
It reads: Obraz Neopalimuiya Kupinui Presvyatuiya Bogoroditsui
OBrAz NeOpAlIMuiiA KupinuI Pres[vya]t[ui]ia B[ogoro]d[i]TSuI
We have seen the inscription in an earlier posting on that icon type, “The Image of the Unburnt Thornbush Most Holy Mother of God.”
Here the beginning of another inscription:
OBRAz VOZDVIZHEN[i]E CHesTNAGO KR[e]sTA G[o]s[pod]NYA
“Image of the Elevation of the Venerable Cross of the Lord”
Notice how the writer of the inscription has used strong vertical lines, and very thin triangular lines to form the “horizontals” at top and bottom of letters. And notice the little flourishes he has placed on the letters here and there. His T letters consist of three, full-length verticals with triangular “horizontals” at the top, but this form is less common.
The best way to learn Vyaz’ calligraphy is to look at lots of different examples, and to copy those one finds most appealing. Some people find it helpful to use graph paper at the beginning, so that the size of varying letters can be carefully measured while writing. And keep in mind that there are lots of variations in just how a particular letter may be ornamented.