For Further Specification

Description

For Further Specification (FFS) is a fundamental administrative and procedural notation within 3GPP Technical Specifications (TS) and Technical Reports (TR). It is not a network function, protocol, or interface, but a tag used by specification writers. When a working group encounters a technical aspect that requires more study, awaits implementation feedback, or is dependent on a decision in another group, they mark it as FFS. This explicitly signals that the current text is incomplete and the detail is intentionally left open.

The use of FFS is governed by 3GPP's specification drafting rules. It is typically applied to parameters, procedures, message fields, algorithms, or even entire functional descriptions. The presence of FFS creates an open issue or "placeholder" that must be resolved before the specification can reach a stable, implementable state. Resolving an FFS item involves technical discussion, consensus-building within the relevant working group, and ultimately the agreement on specific text to replace the FFS marker. This text is then incorporated into a later version of the same specification or, in some cases, a different, referenced specification.

From an architectural and implementation perspective, FFS has a significant impact. Equipment vendors and network operators reading a specification must identify all FFS markers to understand the gaps and risks in the technology. An FFS on a critical parameter can delay product development or lead to interim proprietary solutions. The process of resolving FFS items is a core part of the iterative standardization workflow, ensuring that specifications mature from high-level frameworks to detailed, unambiguous blueprints for interoperable equipment. Its use spans all 3GPP domains, from radio access (e.g., 36-series specs) to core network (29-series) and security (33-series), as indicated by its appearance in dozens of specification documents across releases.

Purpose & Motivation

FFS exists to enable the pragmatic and parallel development of complex telecommunications standards. 3GPP specifications are created by multiple working groups simultaneously, covering different system parts (radio, core, protocols, testing). It is impossible to finalize every minute detail in a single step. FFS provides a formal mechanism to advance the overall specification framework while acknowledging and tracking unresolved technical points.

This solves the problem of specification deadlock. Without FFS, work on a broad section of a spec would halt completely until every minor detail was agreed upon, drastically slowing progress. By using FFS, groups can capture architectural agreements and the majority of a procedure's flow, leaving specific values or algorithmic details for later resolution based on simulation results, implementation experience, or harmonization with other groups. It directly addresses the challenge of managing the interdependence between different parts of a large, system-wide standard. Historically, this notation has been essential from the first 3GPP releases (R99) onwards, allowing the rapid development of foundational specs like the RRC protocol (25.331) while leaving certain parameters for later refinement.

Key Features

• A placeholder marker in 3GPP specification text indicating undefined details
• Used to manage open issues and track unresolved technical points
• Allows parallel development of specification sections without full consensus on all details
• Must be resolved before a specification is considered stable and implementable
• Applies to parameters, procedures, message formats, and algorithms
• Documented across hundreds of 3GPP specifications from all domains

Evolution Across Releases

Defining Specifications