in a different language that may be keywords in a calling language. This is sometimes done by prefixes, such as @ in C#, or enclosing the identifier in brackets, in Visual Basic.NET. A second major example is in many implementations of Structured Query Language. In those languages reserved words can be used as column, table, or variable names by lexically delimiting them. The standard specifies enclosing reserved words in double quotes, but in practice the exact mechanism varies by implementation; MySQL, for example, allows reserved words to be used in other contexts by enclosing them in backticks, and Microsoft SQL Server uses square brackets. Stropping can also be used in the Nim programming language. In Nim, a reserved word can be used as an identifier by enclosing it in backticks. There are other, more minor examples. For example, Web IDL uses a leading underscore _ to strop identifiers that otherwise collide with reserved words: the value of the identifier strips this leading underscore, making this stropping, rather than a naming convention. by the compiler In a compiler frontend, originally occurred during an initial line reconstruction phase, which also eliminated whitespace. This was then followed by scannerless parsing (no tokenization); this was standard in the 1960s, notably for ALGOL. In modern use, is generally done as part of lexical analysis. This is clear if one distinguishes the lexer into two phases of scanner and evaluator: the scanner categorizes the stropped sequence into the correct category, and then the evaluator when calculating the value. For example, in a language where an initial underscore is used to strop identifiers to avoid collisions with reserved words, the sequence _if would be categorized as an identifier (not as the reserved word if) by the scanner, and then the evaluator would give this the value if, yielding (Identifier, if) as the token type and value. Similar techniques A number of similar techniques exist, generally prefixing or suffixing an identifier to indicate different treatment, but the semantics are varied. Strictly speaking, stropping consists of different representations of the same name (value) in different namespaces, and occurs at the tokenization stage. For example, in ALGOL 60 with matched apostrophe stropping, 'if' is tokenized as (Keyword, if), while if is tokenized as (Identifier, if) – same value in different token classes. Using uppercase for keywords remains in use as a convention for writing grammars for lexing and parsing –