Identification
Unfortunately, there are (at least) two senses in which this word is used. They are similar only in the abstract: In the context of manufacturing, the process of marking Part Numbers on parts as they are manufactured. In the context of System Engineering. See Configuration Identification.
Identification Cross-Reference Drawing (ICRD)
A type of Procurement Control Drawing that directs procurement of items from sources (usually commercial) that do not use ASME-compliant product identification, altering the items for part-marking only. The combination of instructions and part-marking effectively incorporates them into an ASME-compliant framework. This drawing type for critical high-performance applications is quite rare, because it is almost impossible to... read more
Identifying Drawing
A drawing that can legitimately, in accordance with ASME Y14.24, be used to assign a Part Number, and is therefore a mandatory contributor to manufacturing of the Identified part.
If and only If (IFF)
A condition possessed by a set of criteria which, in and of themselves, constitute the entire necessary and sufficient conditions for something to be either true or false.
Imaginary Number
Two distinct definitions exist: Any number involving the square root of -1. Typically used in numerically intensive, analytically oriented things like signal processing, control theory, and electromagnetism to assist in (for example) stability analysis, but also sometimes used just to make the math work out right (which was, in fact, the original application). Schedule dates... read more
Incorporation by Reference
Inclusion of a “pointer” in one document to specific information in another document, without inserting the actual content (see value). This admits to the possibility that changes to the former document may, at some future time, be relevant to the development or sustainment of the CI that is the subject of the former. Contrast with... read more
Incremental Development
A developmental strategy in which an end-goal set of requirements are allocated to a CI, but no set sequence of development steps is defined. In effect, motion toward a pre-determined goal in the hopes that there is a road out there, somewhere, just waiting to be found. Contrast with spiral development. In incremental development, knowing... read more
Index Drawing
A drawing having the sole purpose of pointing to other drawings to create an enumerated list (“index”).
Inductive Reasoning
As a crude simplification, inductive reason happens when the facts and data are “incomplete” with respect to the actual domain of the decision being made. In many cases, we create abstract rules and procedures based on “lessons learned”, then apply those generalizations to something else. Because there can be gaps1 in the train of logic,... read more
Information Technology
A ten-dollar turn of phrase having a catchier sound than “computers and networks and stuff”.
Inspection
(1) Direct observation of the article without the use of intrusive instrumentation. Applicable IFF the characteristic specified is both quantifiable and externally observable. This sense is applied only as part of “line QA“, through mandatory features found on the article’s identifying drawing. (2) When used in the context of Qualification, direct observation of the identifying drawing... read more
Integration
In legacy System Engineering, the horizontal and vertical work required to ensure that the various parts of the system worked together through coordinated development of requirements, interfaces, as-designed characteristics, procedures, analyses, and tests. More recently, the relatively simple act of aggregating the various parts into their next higher assemblies.
Interchangeability
An abstract characteristic of two or more articles, both of which meet the Acceptance Requirements relative to the part’s use as intended by the developer. Interchangeability is the primary criterion for assignment of a single Part Number to a purported specimen of some specific design.
Interface (I/F)
The abstract partition separating two or more items into individually identifiable things in the minds of the people working on, with, or around them. As a “logical device”, an I/F describes characteristics of the items, including (but not limited to) measures, states, physical characteristics, and functionality, any or all of which can be either coordinated... read more
Interface Control Document (ICD)
A formal document characterizing an interface. As a formal document, the ICD typically exists only when two legally distinct organizations must coordinate on the development of items that must coexist to some degree of interest to a contractual customer shared by both organizations.
Interface Description Document (IDD)
A normative ICD addressing the salient details of the completed design, often referred to in the legacy as a “Part II ICD”.
Interface Requirements Document (IRD)
A prescriptive ICD addressing the requirements for the as-yet-un-designed items. Referred to in the legacy as a “Part I ICD”.
Interface Requirements Specification (IRS)
A type of specification unique to Software Systems Engineering, where the “interface” was originally a component (e.g., a Graphical User Interface), but that has been generalized to combine the concepts of ICD and Specification which were, in the hardware legacy, two completely different things.
Internal Change
An alteration of planned or intended cost, technical, or schedule content that is entirely in-scope to the contractual authority of the developer or supplier. Such a change does not require notification to the customer prior to incorporation into the design. Contrast with external change.
Internal Research and Development (IRAD)
Internally funded R&D, such that any Intellectual Property belongs to the company. In the context of government work, IRAD is often at least partly compensated by the government. Contrast with CRAD.
Jacobian Matrix
The matrix formed by all first-order partial derivatives of a vector-valued function. The Jacobian can be interpreted as a “map” of how a system will respond to small changes in the value of its independent variables: a matrix of “influence coefficients” or “sensitivity coefficients”. If time is an independent variable, the Jacobean provides limited insight... read more
Keep the program sold
A marketing strategy having to do with protecting the life of a program in spite of the many developmental difficulties it may be facing. The strategy may, or may not, be collusively pursued by both contractor and Acquisition Customer. Sadly, this strategy is a necessary part of getting anything useful done in a bureaucratic environment,... read more
Knowledge
The facts, principles or other objects of perception gained through instruction, study, research or direct experience and (therefore) considered to be of unquestionable certainty. Knowledge, in this context, always results from an intellectual investment. It might (or might not) be cognitively entangled with an associated (possibly biasing) emotional investment. Contrast with belief, and compare to... read more
Latent (Failure, Defect, Cause)
A circumstance or condition present for some significant period of time before other events precipitate its consequence. The term is most often used in the context of Root Cause Analysis.
Layout
“A layout drawing depicts design development requirements. It is similar to a detail, assembly, or installation drawing, except that it presents pictorial, notational, or dimensional data to the extent necessary to convey the design solution used in preparing other engineering drawings. Except as noted…a layout drawing does not establish item identification.”1 ASME Y14.24, section 2.1.[↩]
Leak Test Pervert
The essential Performance Requirements for the ISS Common Berthing Mechanism (CBM) were: The ability to acquire control authority over the in-coming module, parameterized by the number of (3) and separation between points of contact (90 +/- 30 degrees) between the on-orbit module and the in-coming module at the end of “capture”; The ability to establish... read more
Level (1|2|3) Drawing
Three “levels” of Engineering Drawing were defined by the now-defunct DOD-D-1000 “Drawings, Engineering and Associated Lists”. Even though the standard is no longer in use, and has not (to my knowledge) been functionally replaced by an industry standard, the “levels” concept is of some use in establishing a mental organization of how design progresses. It... read more
Limit Condition
The extreme verifiable circumstance or value associated with some exogenous parameter used to measure some kind of load on a part, system, or function thereof. Usually, the limit condition is some amount of margin higher than the highest load actually expected during operations, where the margin accounts for uncertainty in derivation of the value. Noting that... read more
Limited Use
An MRB disposition that approves a Serial Number or Lot Number of an item for use that is more restrictive than the Development Requirements stipulate. For example, a marginally performing part might be limited for use as Test Support Equipment, for non-combat conditions, or for a restricted number of operational hours. Limited Use items require... read more
Line Number (L/N)
A type of accession identifier indicating specific position in a production stream. The line number might, or might not, be indicative of either the order sequence (Effectivity) or planning sequence (S/N).
Linking (software)
The process of stitching together pieces of object code so that all calls to sub-routines point to exactly one location in one piece of object code (“references have been resolved”). Linking results in executable code. Linking can be either static (resolved before run-time), or dynamic (resolved at run-time). Dynamic linking permits asynchronous changes between code... read more
Lookoverherelookoverherelookoverhere
A type of smokescreen that may, or may not1, have been repeatedly executed during development of the Common Berthing Mechanism (sometimes referred to as “the debacle” in certain circles of the ISS SE bureaucracy). No evidence exists. No conviction can be obtained.[↩]
Lot Number (L/N)
The analog of S/N for products having quality that is dominated (perhaps exclusively determined) by the quality of their bulk material composition or highly repetitive fabrication.
Major/Minor Determination
A process used by commercial aircraft developers to determine whether an existing certification remains applicable after incorporating some particular change in the design. This process lies close to the core of how the developer stays in business. The basis of the process is found in 14 CFR 21.93.a : “A ‘minor change’ is one that... read more
Make-from Drawing
This isn’t actually a formally defined drawing type. It simply refers to a drawing that calls and modifies one or more other parts. If the part was purchased in the configuration from which the modification starts, this drawing could be an Altered Item Drawing. Otherwise, it is simply a non-detail production drawing.
Make-on-Assembly
An item that never exists as a stand-alone P/N, but is only fabricated as its constituent elements are joined into its next-higher assembly.
Make-or-Buy Decision
A design process, occurring early in development, assessing the relative cost effectiveness and feasibility of internal development for an item vs. external procurement of that item. The decision strongly influences how things will go afterwards, bringing substantially different skills and tools into play.
Management
In the context of System Engineering, active control based on cost, technical, or schedule status of a project. In this context, “control” means that we’re paying attention to the projected technical adequacy of a CI, when we expect to turn it over to the customer, and how much they’ll have to pay for the privilege. If it... read more
Manufacturing Drawing
A drawing that supplies information for a manufacturing process. These drawings can be either identifying or ancillary. When the manufacturing process is at some significant rate, or under high levels of control, these drawings are sometimes referred to as “production drawings”.
Manufacturing Requirement
A type of requirement imposed on Manufacturing by Engineering. In most cases, a mandatory feature found on an identifying drawing.
Margin
Generally, a dimensioned quantity which, when added to some other quantity of the same property, accommodates uncertainties in 1) knowing the value of that other quantity or 2) knowing the value of capability relevant to that other quantity. Sometimes, a margin will be quoted as a dimensionless additive value (when it is “normalized” to some... read more
Master Verification Plan (MVP)
The intent of an MVP is to describe the broad outlines of how verification is approached on a complicated program. The benefit of having a technically competent MVP is that it can provide context for the approach, showing how the major activities relate to each other. However, MVP’s can attempt to control too much detail,... read more
Material Review Board (MRB)
An MRB is a formally chartered group of people empowered to supersede or direct the change of certain aspects of published Engineering during production. The MRB concept is important to SE because under certain circumstances, the board members can authorize temporary or limited invalidation of qualification data. The process is not normally tied to the... read more
Mathematics
Patterns of manipulating quantities or representations thereof. The subject patterns may be either concrete or abstract. read more.
May (usage of)
Information given to the developer with regard to a characteristic which, if not met by the proffered design, need not be explained away by the developer. In other words…not a requirement at all, just a good idea. This form is now generally deprecated. Contrast with shall, shall-where-practicable, should, and will.
Measure
(1) As a verb: the act of verifying a quantity by inspection. (2) As a vernacular noun: a seldom-used term referring to a quantifiable property or attribute of a thing. The “thing” itself can be either concrete or abstract. The usage arises from legacy System Engineering practice with respect to requirements, referring to a property... read more
Measure of Constraint
A parameter used to quantify the nature of a constraint (meaning 1).
Measure of Performance
A parameter used to quantify the execution of a function. read more.
Memory Address
A specific location in a memory space, having a size determined by the computer and (often) the OS.
Memory Space
The list of (usually contiguous) memory addresses available to a process.
Metric Space
A space for which a true "distance" is defined. read more.
Middle-ware
Software that manages communication between (possibly dissimilar) computers. Examples of middle-ware functions include data type abstraction, data marshalling, endian swaps and network abstraction so that the computers on all sides correctly interpret the raw data when presented to them. From the perspective of the programmer, middle-ware can be a special case of Application Software, supporting... read more
MIL-HDBK-245
Handbook for Preparation of Statement of Work (SOW).
MIL-S-83490
A now-canceled standard for specification practices. The immediate predecessor to MIL-STD-490. MIL-S-83490 used a “Part I/Part II” specification nomenclature, which exactly corresponded to the more recent “B-spec/C-Spec” nomenclature of MIL-STD-490.
MIL-STD-1521
A now-canceled standard governing the content of various technical reviews and audits. This document was the basis for PDR, CDR, and FCA for decades.
MIL-STD-490
A now-canceled standard for specification practices. The immediate predecessor to MIL-STD-961 (at revision D).
MIL-STD-499
A now-canceled standard for System Engineering Management.
MIL-STD-961
The standard that succeeded MIL-STD-490 at Revision D. It was upgraded to attempt addressing development specifications after MIL-STD-490 was canceled. It never really did the job. Standards for specification practices headed downhill fast with (and following)MIL-STD-961. To be honest, they got so bad that I quit paying attention around the turn of the century. Maybe... read more
Military-Industrial Complex
President Eisenhower coined this term in his 1961 Farewell Address. The basic concept is that the contractors and the uniformed Military forces have figured out that more and better weapons means they both get more power and more money…and they’ll pull any and all strings necessary to make that happen. There have been arguments about... read more
Miss’ippi State
If you can’t pronounce it right, they wouldn’t likely let you in the door, anyway.
Mode
I am aware of no useful definition of “mode” that is universally1 accepted in System Engineering. I have, however, used “mode” to indicate a group of functions, none of which are disabled by some supervisor or executive2. That is, within a single “functional mode”, any given function of that mode can execute according to whatever... read more
Model
A system of postulates, data, and inferences presented as a mathematical description of an entity or state of affairs. read more.
Model Number
In common usage, a marketing fiction permitting a single (but not legally binding) description to remain constant for relatively long periods of time. Two items may carry the same model number and yet not be interchangeable. Contrast with Part Number.
Model-based System Engineering (MBSE)
Assuming the definition of model is about right, MBSE simply creates a model of some kind as the specification. What I find fascinating is that the legacy concept of a specification (see, for example, MIL-STD-490) actually meets that description1. This notion is, apparently, lost on the people who have seized on the MBSE buzzword. Most... read more
Multi-lateral ICD
A type of ICD having addressing characteristics jointly held by more than a single CI. Contrast with unilateral ICD.
Multi-Purpose Drawing
It is legitimate to have a single drawing that acts as more than a just one drawing type. A good example is to start with an existing item from any one of several different suppliers (see Vendor Item Control Drawing), screen the parts to get only the really good ones (see Selected Item Drawing), then... read more
Newman, Alfred E.
The logo of the now nearly defunct MAD Magazine. Mr. Newman’s picture was understood as a synonym for the magazine’s slogan “What, me worry?”. The relevance to certain System Engineering and management practices should be self-evident.
Non-cognoscenti
Those who are without a technical clue about the problem at hand. Including, but not limited to, non-SME’s.
Non-complex Item
In the MIL-STD-490 context, a CI that is not complicated enough or important enough to be considered “critical” (as in “Critical Item”).
Non-Conformance (NC)
A situation in which some allocated requirement is determined to not be met by a design (in the case of qualification) or by a S/N or lot (in the case of acceptance).
Normalization
The mathematical process of transforming a data set into a Gaussian (“normal”) distribution, so that standard statistical concepts (e.g, mean, median, variance, kurtosis) are valid. Unless the data have been verified as conforming or transforming into the Gaussian shape, no parametric statistics should be trusted. Note that this verification process “consumes” degrees of freedom in... read more
Notional Design
In the legacy System Engineering processes, the first development phase established a conceptual design for a system. At the end of that phase, the intent was to have identified the characteristic functions of the system, along with other defining non-functional characteristics that distinguish it from other conceptual systems, without having unduly constrained the range of... read more
Numerical Methods
Numerical methods use numerical approximation rather than symbolic algebra to estimate solutions to Engineering problems to within some practical limit of uncertainty. In this context, “practical” can refer to the limits of calculational precision or to the limit of Experimental Uncertainty during a model-validating test, or to the limit of tolerance in an allocated requirement. Most of these... read more
Numerical Stability
A property of computational processes such that small changes in the input(s) result in small changes of the output(s). “Small” is, of course, relative to the nature of the computation and usage of the result. Issues of numerical stability can produce a highly non-linear component of uncertainty, leading to highly variable tolerances.