-\usepackage[T2A]{fontenc}
-\usepackage[utf8]{inputenc} % file encoding
-\usepackage{substitutefont} % so we can use fonts other than those specified in babel
-\usepackage[english]{babel} % default language for document
-\usepackage[scaled=0.925]{XCharter} % Подключение русифицированных шрифтов XCharter
-\usepackage[bitstream-charter]{mathdesign} % Согласование математических шрифтов
+\usepackage[T2A]{fontenc} % T2A (Cyrillic) and T1 are only identical
+ % in the first 128 positions. This is an
+ % English language document.
+\usepackage[utf8]{inputenc} % file encoding
+\usepackage{substitutefont} % so we can use fonts other than those specified in babel
+\usepackage[english]{babel} % default language for document
+% Cyrillic - if it is used, no Small Caps are available:
+%\usepackage[scaled=0.925]{XCharter} % Подключение русифицированных
+ % шрифтов XCharter "Connection
+ % of Russified XCharter Fonts"
+\usepackage[bitstream-charter]{mathdesign} % Согласование
+ % математических шрифтов
+ % "Math font
+ % harmonization"