eSignal EFS function library file
File type: Accounting, financial and tax file
The .efslib file extension identifies an EFS function library file used by eSignal trading software.
The file stores reusable functions for eSignal Formula Script (EFS) formulas and is intended to work as part of the eSignal EFS environment.
File type category:
Accounting, financial and tax file
Date updated: September 28, 2026
An eSignal EFS function library file contains function library data used by EFS scripts. It provides reusable functions that EFS formulas can use instead of defining the same code repeatedly in each formula.
The format is specific to eSignal, the Microsoft Windows online trading software, and is not a general-purpose financial data exchange format. The file normally works as a supporting component of an EFS formula rather than as a standalone document.
Use eSignal on Microsoft Windows to use an .efslib file. The file is normally loaded as an EFS library for a formula through eSignal's EFS tools, rather than opened as a standalone document.
There is no standard conversion for an eSignal EFS function library file. Its purpose is to provide reusable code to eSignal EFS formulas, so converting it to another file format would remove its normal use in eSignal.
To use the functions in another scripting environment, they must be recreated or manually rewritten for that environment. Keep the .efslib extension when the library is intended for eSignal.
Software applications that can open efslib files:
Microsoft Windows
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