# EPOC OPL Guide & Reference Glossary

## Index D

Term | Topic | Meaning | See Also
database | Data File Handling | A body of data which can be searched or browsed by OPL. In OPL, databases are arranged as one or more tables, and can be queried using SQL, a standard database query language. OPL can import the database format used by the EPOC Data application. This system documentation also uses ‘database’ to refer to the disk file used to store the data. | record, field, SQL, table, view
DBMS | Data File Handling | The Database Management System. The EPOC DBMS is a service of the operating system that can be used by programs to access and share databases safely and efficiently. | database
declare | OPL Basics | To define the name of a variable and its scope. |
denormal | OPL Basics | A floating-point number in the range 5E-324 to 2.2250738585072015E-308. | floating-point
deprecated | Keyword Reference | A marker meaning that an item is liable to either change or be removed in future versions, or that using the item in the current release is unwise. OPL features and keywords which are included to maintain compatibility with previous versions of OPL, but which have no current use or which have been superseded by newer and better keywords are marked deprecated to indicate that they should no longer be used. Deprecation does not necessarily imply that the keyword will be phased out. |
dither | Graphics and Interaction | To emulate a colour in a colour mode that cannot display the colour exactly. The screen appearance of the colour is emulated by a mathematical stippling of pixels in colours that the mode can display exactly. | colour mode
DLL | Using OPXs | A Dynamically Loaded Library. A file used by EPOC to store compiled functions in native machine language (compiled from C++). DLLs can be used by many different programs at once, so storing the code for a function in a DLL is efficient — you don’t have to keep copies of the same thing in each program you want to write. OPXs are a special form of DLL that can be used by OPL programs. The EPOC C++ SDK can be used to write DLLs for EPOC. | Linked by ordinal
document | Advanced Topics | A file which will run your application when started from the system screen. Documents can also store information, such as an OPL module. Each document belongs to a particular application, and has an icon that looks like the application’s icon. |