VisualBasic for Scientific Computing.zip

# The NetCDF Classic Format Specification > https://www.unidata.ucar.edu/software/netcdf/docs/file_format_specifications.html To present the format more formally, we use a BNF grammar notation. In this notation: + Non-terminals (entities defined by grammar rules) are in lower case. + Terminals (atomic entities in terms of which the format specification is written) are in upper case, and are specified literally as US-ASCII characters within single-quote characters or are described with text between angle brackets (``<`` and ``>``). + Optional entities are enclosed between braces (``[`` and ``]``). + A sequence of zero or more occurrences of an entity is denoted by ``[entity ...]``. + A vertical line character (``|``) separates alternatives. Alternation has lower precedence than concatenation. + Comments follow ``//`` characters. + A single byte that is not a printable character is denoted using a hexadecimal number with the notation ``\xDD``, where each D is a hexadecimal digit. + A literal single-quote character is denoted by ``\'``, and a literal back-slash character is denoted by ``\``. Following the grammar, a few additional notes are included to specify format characteristics that are impractical to capture in a BNF grammar, and to note some special cases for implementers. Comments in the grammar point to the notes and special cases, and help to clarify the intent of elements of the format. ## The Format in Detail ``` netcdf_file = header data header = magic numrecs dim_list gatt_list var_list magic = 'C' 'D' 'F' VERSION VERSION = \x01 | // classic format \x02 // 64-bit offset format numrecs = NON_NEG | STREAMING // length of record dimension dim_list = ABSENT | NC_DIMENSION nelems [dim ...] gatt_list = att_list // global attributes att_list = ABSENT | NC_ATTRIBUTE nelems [attr ...] var_list = ABSENT | NC_VARIABLE nelems [var ...] ABSENT = ZERO ZERO // Means list is not present ZERO = \x00 \x00 \x00 \x00 // 32-bit zero NC_DIMENSION = \x00 \x00 \x00 \x0A // tag for list of dimensions NC_VARIABLE = \x00 \x00 \x00 \x0B // tag for list of variables NC_ATTRIBUTE = \x00 \x00 \x00 \x0C // tag for list of attributes nelems = NON_NEG // number of elements in following sequence dim = name dim_length name = nelems namestring // Names a dimension, variable, or attribute. // Names should match the regular expression // ([a-zA-Z0-9_]|{MUTF8})([^\x00-\x1F/\x7F-\xFF]|{MUTF8})* // For other constraints, see "Note on names", below. namestring = ID1 [IDN ...] padding ID1 = alphanumeric | '_' IDN = alphanumeric | special1 | special2 alphanumeric = lowercase | uppercase | numeric | MUTF8 lowercase = 'a'|'b'|'c'|'d'|'e'|'f'|'g'|'h'|'i'|'j'|'k'|'l'|'m'| 'n'|'o'|'p'|'q'|'r'|'s'|'t'|'u'|'v'|'w'|'x'|'y'|'z' uppercase = 'A'|'B'|'C'|'D'|'E'|'F'|'G'|'H'|'I'|'J'|'K'|'L'|'M'| 'N'|'O'|'P'|'Q'|'R'|'S'|'T'|'U'|'V'|'W'|'X'|'Y'|'Z' numeric = '0'|'1'|'2'|'3'|'4'|'5'|'6'|'7'|'8'|'9' // special1 chars have traditionally been // permitted in netCDF names. special1 = '_'|'.'|'@'|'+'|'-' // special2 chars are recently permitted in // names (and require escaping in CDL). // Note: '/' is not permitted. special2 = ' ' | '!' | '"' | '#' | '$' | '' | '&' | '\'' | '(' | ')' | '*' | ',' | ':' | ';' | '<' | '=' | '>' | '?' | '[' | '\' | ']' | '^' | '‘’ | '{' | '|' | '}' | '~' MUTF8 = <multibyte UTF-8 encoded, NFC-normalized Unicode character> dim_length = NON_NEG // If zero, this is the record dimension. // There can be at most one record dimension. attr = name nc_type nelems [values ...] nc_type = NC_BYTE | NC_CHAR | NC_SHORT | NC_INT | NC_FLOAT | NC_DOUBLE var = name nelems [dimid ...] vatt_list nc_type vsize begin // nelems is the dimensionality (rank) of the // variable: 0 for scalar, 1 for vector, 2 // for matrix, ... dimid = NON_NEG // Dimension ID (index into dim_list) for // variable shape. We say this is a "record // variable" if and only if the first // dimension is the record dimension. vatt_list = att_list // Variable-specific attributes vsize = NON_NEG // Variable size. If not a record variable, // the amount of space in bytes allocated to // the variable's data. If a record variable, // the amount of space per record. See "Note // on vsize", below. begin = OFFSET // Variable start location. The offset in // bytes (seek index) in the file of the // beginning of data for this variable. data = non_recs recs non_recs = [vardata ...] // The data for all non-record variables, // stored contiguously for each variable, in // the same order the variables occur in the // header. vardata = [values ...] // All data for a non-record variable, as a // block of values of the same type as the // variable, in row-major order (last // dimension varying fastest). recs = [record ...] // The data for all record variables are // stored interleaved at the end of the // file. record = [varslab ...] // Each record consists of the n-th slab // from each record variable, for example // x[n,...], y[n,...], z[n,...] where the // first index is the record number, which // is the unlimited dimension index. varslab = [values ...] // One record of data for a variable, a // block of values all of the same type as // the variable in row-major order (last // index varying fastest). values = bytes | chars | shorts | ints | floats | doubles string = nelems [chars] bytes = [BYTE ...] padding chars = [CHAR ...] padding shorts = [SHORT ...] padding ints = [INT ...] floats = [FLOAT ...] doubles = [DOUBLE ...] padding = <0, 1, 2, or 3 bytes to next 4-byte boundary> // Header padding uses null (\x00) bytes. In // data, padding uses variable's fill value. // See "Note on padding", below, for a special // case. NON_NEG = <non-negative INT> STREA