are stropped as .EQ. etc. (see below) UPPER for 7-bit, as in FOR – with lowercase used for ordinary identifiers QUOTE as in ALGOL 60, as in 'for' RES reserved words, as used in modern languages – for is reserved and not available to ordinary identifiers The various rules regimes are a lexical specification for stropped characters, though in some cases these have simple interpretations: in the single apostrophe and dot regimes, the first character is functioning as an escape character, while in the matched apostrophes regime the apostrophes are functioning as delimiters, as in string literals. Other examples: Atlas Autocode had the choice of three: keywords could be underlined using backspace and overstrike on a Flexowriter keyboard, they could be introduced by a %percent %symbol, or they could be typed in UPPER CASE with no delimiting character ("uppercasedelimiters" mode, in which case all variables had to be in lower case). Algol 60 on the Elliott 803 and Elliott 503 computers used underlining. The Flexowriters (producing punched paper tape) had a non-movement key (underline _) so that typing _b_e_g_i_n produced begin which was very readable. The vertical bar | was also a non-movement key so that typing |= produced a good approximation to ≠. The Kidsgrove compiler for Algol 60 on the English Electric KDF9 appears to have used at least two other stropping conventions in addition to quotation marks: exclamation marks and Percent characters. ALGOL 68RS programs are allowed the use of several stropping variants, even within the one language processor. Edinburgh IMP inherited the Atlas Autocode %percent %symbol prefix convention but not its other stropping options Examples of different ALGOL 68 styles Note the leading pr (abbreviation of pragmat) directive, which is itself stropped in POINT or quote style, and the for comment (from "") – see ALGOL 68: pr & co: Pragmats and Comments for details. Other languages For various reasons Fortran 77 has these "logical" values and operators: .TRUE., .FALSE., .EQ., .NE., .LT., .LE., .GT., .GE., .EQV., .NEQV., .OR., .AND., .NOT. .AND., .OR. and .XOR. are also used in combined tests in IF and IFF statements in batch files run under JP Software's command line processors like 4DOS, 4OS2, and 4NT / Take Command. Modern use Most modern computer languages do not use stropping, with two notable exceptions: The use of many languages in Microsoft's .NET Common Language Infrastructure (CLI) requires a way to use variables