DSTV profile types: I, U, L, B, RO, RU, M, C, T

Line 8 of every NC1 file's ST header carries a short profile type code. It is arguably the most important value in the file: it tells the consuming machine (or viewer) what cross-section shape the part has, which faces exist, and how to interpret every coordinate in the hole and contour blocks that follow. Get the profile code wrong and a hole "on the web" lands on a flange.

The codes

Code	Shape	Typical sections
`I`	I / H sections (beams and columns)	IPE, HEA/HEB/HEM, W-shapes, UB/UC
`U`	Channels	UPN/UPE, C and MC shapes, PFC
`L`	Angles	Equal and unequal leg angles
`B`	Plate / flat (Blech)	Base plates, gussets, stiffeners, flats
`RO`	Round tube (Rohr)	CHS, pipe
`RU`	Round bar (Rundstahl)	Solid rounds, anchor rods
`M`	Rectangular / square hollow section	RHS, SHS, HSS tube
`C`	Cold-formed C profiles	Purlins and similar
`T`	T-sections	Rolled tees, split beams
`SO`	Special / other	Anything not covered above

How faces map onto each shape

DSTV describes work per face (v front/web, o top, u bottom, h rear — see the block codes guide). Which faces physically exist depends on the profile type:

I-sections (I): v is the web, o/u are the top and bottom flanges. Flange holes measure Y across the flange width; web holes measure Y up the profile height.
Channels (U) and C profiles (C): like an I-section but the web sits at one side; h (rear) addresses the back of the web — a face an I-beam does not use for drilling.
Angles (L): two legs — typically v for one leg and o or u for the other, with the heel as reference.
Plates (B): one working face (v); the outer contour block (AK) does most of the talking, and KA bend lines may appear for folded plates.
Hollow sections (M, RO): four faces for rectangular tube; round tube positions are effectively unrolled along the circumference. Through-drilling both walls appears as holes on opposite faces.
T-sections (T): a web plus a single flange, so v and one of o/u.

The header dimensions that go with the code

After the profile code and the profile name (e.g. HEA200, W14X90, RHS 100x100x8) the header lists numeric dimensions — length, height, width, flange thickness, web thickness, radius, weight per metre. Machines generally trust these numbers over any catalog lookup, because the file must stand alone. A good viewer cross-checks them: NC1-Viewer.com ships a profile catalog derived from standard section databases and flags dimensions that look inconsistent with the named profile.

Practical gotchas

Plates exported as I: some CAD add-ins export everything as I-profiles with zero flange thickness. Machines cope; humans get confused.
RO vs RU: tube versus solid bar — one wall thickness field distinguishes them; a missing value can flip the interpretation.
Imperial names, metric numbers: a W14X90 section in an NC1 file still carries millimetre dimensions; the name is only a label.
Unequal angles: check which leg the exporter treats as v — conventions differ between packages.

See your profile rendered

NC1-Viewer.com renders all of the profile types above in 2D face views and 3D, so you can confirm at a glance that the profile code, dimensions, and hole faces agree.

Open an NC1 file in the free viewer →