A production or production rule in computer science is a rewrite rule specifying a symbol substitution that can be recursively performed to generate new symbol sequences. A finite set of productions is the main component in the specification of a formal grammar (specifically a generative grammar). The other components are a finite set of nonterminal symbols, a finite set (known as an alphabet) of terminal symbols that is disjoint from and a distinguished symbol that is the start symbol.
In an unrestricted grammar, a production is of the form where and are arbitrary strings of terminals and nonterminals however may not be the empty string. If is the empty string, this is denoted by the symbol , or (rather than leave the right-hand side blank). So productions are of the form:
The other types of formal grammar in the Chomsky hierarchy impose additional restrictions on what constitutes a production. Notably in a context-free grammar, the left-hand side of a production must be a single nonterminal symbol. So productions are of the form:
A record producer (or music producer) has a very broad role in overseeing and managing the recording (i.e. "production") of a band or performer's music. A producer has many roles that may include, but are not limited to, gathering ideas for the project, selecting songs and/or session musicians, proposing changes to the song arrangements, coaching the artist and musicians in the studio, controlling the recording sessions, and supervising the entire process through audio mixing (recorded music) and, in some cases, to the audio mastering stage. Producers also often take on a wider entrepreneurial role, with responsibility for the budget, schedules, contracts, and negotiations.
In the 2010s, the recording industry has two kinds of producers with different roles: executive producer and music producer. Executive producers oversee project finances while music producers oversee the creation of music.
A music producer can, in some cases, be compared to a film director, with noted practitioner Phil Ek describing his role as "the person who creatively guides or directs the process of making a record, like a director would a movie. The audio engineering [person] would be more the cameraman of the movie." Indeed, in Bollywood music, the designation actually is music director. The music producer's job is to create, shape, and mold a piece of music. The scope of responsibility may be one or two songs or an artist's entire album– in which case the producer will typically develop an overall vision for the album and how the various songs may interrelate.
Fields that contain a fixed number of bits are known as fixed length fields. A four byte field for example may contain a 31 bit binary integer plus a sign bit (32 bits in all). A 30 byte name field may contain a persons name typically padded with blanks at the end.
The disadvantage of using fixed length fields is that some part of the field may be wasted but space is still required for the maximum length case. Also, where fields are omitted, padding for the missing fields is still required to maintain fixed start positions within a record for instance.