If you intended to mean something else — e.g., a female schematic connector (like a tube socket outline) or a schematic of a tube-based sequencer — please clarify. Otherwise, the above covers a complete technical feature of a tube as drawn in schematics, including internal structure, symbol conventions, and real-world usage.
CRTs have largely been replaced by newer technologies like LCD (Liquid Crystal Display), LED, OLED (Organic Light-Emitting Diode), and plasma displays. These newer technologies offer thinner designs, lower power consumption, and less hazardous materials (like lead, found in CRTs). a schemale tube