From http://www1.bell-labs.com/project/wwexptools/cscope/cscope.html

File format:
    <Header>
    <first file symbol data>
         ...
    <last file symbol data>
    <Trailer>

Header:
    cscope <format version> <current dir> [-c] [-q <symbols>] [-T] <trailer offset>

For each file:
    <file mark><file path>
    <empty line>

For each source line with symbol:
    <line number><blank><non-symbol text>\n
    <optional mark><symbol>\n
    <non-symbol text>\n
    ..repeat above 2 lines as necessary
    <empty line>\n

Symbol data for last file ends with
    <file mark>

A mark is a tab followed by one of these characters:

    Char   Meaning
    ----   -------------------------------------------
    @      file
    $      function definition
    `      function call
    }      function end
    #      #define
    )      #define end
    ~      #include
    =      direct assignment, increment, or decrement
    ;      enum/struct/union definition end
    c      class definition
    e      enum definition
    g      other global definition
    l      function/block local definition
    m      global enum/struct/union member definition
    p      function parameter definition
    s      struct definition
    t      typedef definition
    u      union definition

The trailer contains lists of source directories, include directories, and source files.
Trailer:
    [<number of viewpath nodes>
    <first directory in viewpath, if any>
         ...
    <last directory in viewpath>]
    <number of source directories>
    <first source directory path (always .)>
         ...
    <last source directory path>
    <number of include directories>
    <first include directory path>
         ...
    <last include directory path (normally /usr/include)>
    <number of source and included files>
    <length of string space needed>
    <first file path>
         ...
    <last file path>


###########################################

Where is this symbol used?
Where is it defined?
Where did this variable get its value?
What is this global symbol's definition?
Where is this function in the source files?
What functions call this function?
What functions are called by this function?
Where does the message "out of space" come from?
Where is this source file in the directory structure?
What files include this header file?

After the database is  ready  cscope  will  display  these
input fields:

    Find this C symbol:
    Find this definition:
    Find functions called by this function:
    Find functions calling this function:
    Find assignments to:
    Change this grep pattern:
    Find this egrep pattern:
    Find this file:
    Find files #including this file:

From http://cscope.sourceforge.net/cscope_vim_tutorial.html :

    Char    Meaning
    ----    -------------------------------------------
*   s       all the uses of the symbol
    g       finds the global definition(s) of a symbol
*   c       finds all calls to a function
    f       opens the filename under the cursor


* Since ctags handles lookup of the definitions, cscope should handle
 "find all calls to a function" and "all uses of the symbol" (in that order).

From: http://cscope.sourceforge.net/cscope_maps.vim

    " The following maps all invoke one of the following cscope search types:
    "
    "   's'   symbol: find all references to the token under cursor
    "   'g'   global: find global definition(s) of the token under cursor
    "   'c'   calls:  find all calls to the function name under cursor
    "   't'   text:   find all instances of the text under cursor
    "   'e'   egrep:  egrep search for the word under cursor
    "   'f'   file:   open the filename under cursor
    "   'i'   includes: find files that include the filename under cursor
    "   'd'   called: find functions that function under cursor calls
