Variable Message Format (VMF) & Combat Net Radio (CNR) Basic Course

VMF & CNR Basic is an introductory course providing a concise insight in to both areas.


VMF & CNR Basic expands upon those areas covered within the EO with the duration being one day. Attendees will explore K-Series messages, reporting and addressing. The basic course will additionally discuss Types of Service and Network Access Control as employed by MIL-STD-188-220 compliant systems. Finally, the OPTASK Link CNR Segment and the operational use of VMF through a Digitally Aided Close Air Support (DACAS) scenario will be provided.

Target Audience:

Any person requiring a basic level of understanding of both VMF & CNR, network architecture and basic operational use

Learning Outcomes:

  • Recognise the components of a VMF system
  • State the three US technical documents associated with VMF
  • Identify why header and K-Series message length are variable
  • Explain VMF networks
  • Recognise and discuss issues surrounding employing VMF
  • Identify the number of Functional Area Designators
  • Recognise the three minimum implementation K-Series messages
  • Discuss the issues surrounding header interoperability (IO)
  • Identify who URNs are allocated to
  • Describe EISN & EIRN
  • Discuss the three ways in which Type of Service (TOS) differ
  • State which TOS operates without acknowledgement
  • Identify the TOS employed by a Class A station
  • Recognise why delays are utilised within VMF networks
  • Discuss the Timeout Period length
  • Discuss the strengths and weaknesses of the two mandatory NAD schemes
  • Recall the four types of Data Link address as defined within MIL-STD-188-220
  • Identify the single octet Data Link address range
  • Recognise and correctly interpret all Sets & Fields within OPTASK Link CNR Segment
  • Recall the advantages and disadvantages of DACAS
  • Discuss a basic DACAS scenario

Learning Methods:

Visual, Oral, Verbal, Logical, Social (interpersonal) and Solitary (intrapersonal)

Program Benefits:

  • Recognise the issues surrounding interoperability
  • Discussion of the key addressing components and their importance
  • Impact of VMF upon the Australian Joint Data Network
  • Discussion on how VMF is employed operationally through DACAS scenario


  • VMF & CNR Introduction
  • Functional Area Designators & K-Series Messages
  • Application Header
  • Unit Reference Number & Entity Reporting
  • Types of Service
  • Network Access Control
  • Addressing Techniques
  • OPTASK Link CNR Segment
  • Basic VMF DACAS Operations

Upcoming Workshops

Name Date Time Location Cost
Variable Message Format (VMF) & Combat Net Radio (CNR) Basic Course 13 November 2019 08:30 am - 04:30 pm Auckland New Zealand $1,000.00
Variable Message Format (VMF) & Combat Net Radio (CNR) Basic Course 19 February 2020 08:30 am - 04:30 pm Wellington New Zealand $1,000.00


NOTE: Courses are subject to cancellation if insufficient student numbers.

You will be notified a minimum of 4 weeks prior to the course commencement.

You will not be charged until the course is confirmed.