Generally, SNOMED CT descriptions begin with an upper case letter; the rest of the words in the description lower case except for abbreviations, proper nouns, i.e. names of people, organizations, taxonomic groups (e.g. species, genus, family), etc.
With regard to organism naming:
|Case Sensitivity Indicator||Values||Meaning||Examples|
First letter of the description may or may not be capitalized while the case of the rest of the description cannot be changed
Cannot change any case in the description
Changing case may change the meaning of the term or is not commonly used
Entire description may be lower or upper case
Changing case does not change the meaning of the term
Special attention is to be paid to the possibility of altering the semantics of those concepts whose FSN uniqueness depends upon case significance.
The subtypes of 365638007 |Finding of Rh blood group (finding)| vary in meaning depending upon the description's case of the letters c, d, and e.
Figure 1: Stated view of 365638007 |Finding of Rh blood group (finding)| and subtypes
Case sensitivity can be changed on an existing description without inactivating it.
The common name for |Structure of pharyngotympanic tube (body structure)| is eustachian tube. While the term originated eponymously, it is not the name of the person from whom the body structure was named after. Therefore, the case significance is ci for case insensitive.
Numeric values will not display differently if switched between upper and lower case, so numeric values should be treated as case insensitive characters in a term.
If a description begins with a numeric value and the word following the number does not begin with a capital letter, the case sensitivity indicator is ci for Entire term case insensitive.
If a description begins with a numeric value and follows with an abbreviation that contains a capital letter, the case sensitivity indicator is cl for Initial character case insensitive.
Special characters such as <, %, >, . , &, ^, will not display differently if switched between upper and lower case, so numeric values should be treated as case insensitive characters in a term. The rules for numeric values apply similarly to special characters.
If a description begins with a special character and the word(s) and/or symbol(s) following the special character begins with a capital letter, the case sensitivity indicator is cl for Initial character case insensitive.
Greek alphabet characters
Words derived from the Greek alphabet, for example, alpha, beta, delta, gamma, omega, and etc. are all case insensitive wherever they are in the description.
SNOMED CT descriptions representing assessment scales and staging systems should be capitalized per the name of the scale or staging system. Legacy concepts may not follow this pattern.
Fagerstrom test for nicotine dependence (assessment scale)
Gram staining is a common laboratory technique used to differentiate bacteria based on their cell wall constituents. Laboratory test results may be Gram positive or Gram negative. The technique was developed by a Danish physician, Hans Christian Gram. Consequently Gram, when referring to the technique, should always begin with an upper case G.