Object Code
Machine-readable code produced as by compilation. May, or may not, be executable depending on whether linking is required in order to resolve all sub-routine calls.
Object-Oriented
A conceptual design-organizing approach that packages an entity’s functionality with other features. The term was (apparently) invented for Software development, but the description exactly corresponds to legacy System Engineering practices with regard to identification and population of Specifications, Drawings, and ICD’s to define CI’s. Many software environments ascribe additional characteristics to this notion. For the... read more
Objective Function
In optimization theory, the equation (function) to be maximized or minimized, subject to constraints. If the concept is applied to SE, then the objective function for development is parameterized by the Measures of Requirement as allocated by way the development specification. We have to be careful with this concept, however, because it is tempting to... read more
Objective Requirement
Not, in fact, a requirement at all unless the customer explicitly identifies (in the SoW or T&C) some time, event, or circumstance at which it becomes mandatory, in which case they would more properly be represented by classification of the CI in question. Usually, just an indication of what the customer wishes they could have, if... read more
One-off
The developmental situation in which only a single article is to be produced. Except for very special cases, full-blown developmental and production rigor is very rarely imposed in this situation.
Ontology
A type of classification scheme identifying the kinds of things that exist and the relationships between them. The “things” can be either concrete or abstract, or a mixture of the two. A real-world instance of a thing can possess the attributes of more than one ontological class, so this concept admits to the notion of... read more
Operating Procedure
Design-specific procedures interactive with a dingus which, when executed in the real world by the End User, makes that dingus do its thingus as intended by the developer.
Operating System (OS)
Software (which might be implemented as firmware) used by a computational device to manage the hardware and provide a logical interface for Application Software to request I/O services or task management services. By itself, an OS (e.g., Unix, Windows, Linux) usually has little utility to an End User until application software is installed. An OS typically functions... read more
Operational Analysis
A type of analysis that identifies sequences of action taken by the (possibly prospective) End User. This analysis is typically parameterized based on the effect (possibly merely desired) on circumstances (e.g., conditions, targets, aggressors).
Operational Requirement
A requirement written with regard to what the End User intends to accomplish by the use of a CI or system of CI’s (which may, or may not, have been developed under a single contract with a single developer). The parameterization of an operational requirement need not be restricted to characteristics of the CI(s) or... read more
Operational Requirements Document (ORD)
A legacy-practice collection of operational requirements, typically addressing the entirety of all developmental spirals and increments in a single document. Contrast with CRD.
Operations Research and System Analyst (ORSA)
Craig Naudain (SAIC) once described the difference between a System Engineer (SE) and an Operations Research and System Analyst (ORSA) as follows: an SE is the guy who tells the General he’ll go figure out an answer to the General’s problem. An ORSA is the guy who tells the General he’ll go figure out a... read more
Order
The dimensionality of an array; the number of indices necessary to access exactly one position (a.k.a., “element”). Rank and degree are sometimes used as synonyms, but can have special implications in certain usages. Scalars have zero order, vectors are of order one and matrices are of order two. Arrays can be of any order.
Ordinary Differential Equation (ODE)
In analysis, an ODE is an equation where all of the terms share the same (single) continuous independent variable and/or derivatives with respect to it. The independent variable is often time, but can be any other technically relevant variable for which data are available. Contrast with PDE and DAE.
Original Equipment Manufacturer (OEM)
An OEM makes a part that is sold to for End Use in some other guise (possibly in addition to being offered commercially by the OEM itself). In our context, the original part might (for example) be part of some next-higher assembly, or might be designated for our purpose as an interchangeable part by a... read more
Parameter
A heavily over-loaded term. The meaning strongly depends on the usage, and no attempt is made here to cover all of them. Typically, some kind of variable in the sense of algebra…but not always!
Part I Interface Control Document
A legacy term for an Interface Requirements Document.
Part I Specification
A legacy term (MIL-S-83490) for a development specification.
Part II Interface Control Document
A legacy term for an Interface Description Document.
Part II Specification
A legacy term (MIL-S-83490) for a product/fabrication specification.
Part Number (P/N)
A type of accession identifier uniquely identifying a single stockable item, all specimens of which are interchangeable for the purpose intended by the developer when creating the design. This is the number marked on the part, or on the container if the part’s surface or container if the part’s size or usage precludes direct marking.
Partial Differential Equation (PDE)
A PDE is a differential equation having more than one continuous independent variable (and derivatives with respect to thereto). Contrast with ODE and DAE.
Pearl Harbor File
A collection of concrete evidence, kept on the down-low, that none of the bad things that happened were the fault of the keeper of the file. See also Plan C.
Performance Requirement
A requirement derived from a Function by identifying a Measure of Performance (MoP), supplying units and tolerance, and identifying the circumstances under which the MoP must obtain certain ranges of value.
Physical Characteristic
A feature of a design or CI that is directly accessible to one or more of the five classically-defined human senses. Contrast with Function, which is more abstract, generally requiring inference in order to be detected (and, therefore, verified).
Physical Configuration Audit (PCA)
A formal audit establishing the ability of a manufacturing facility (or set of facilities) to acceptably produce Serial Numbers (or lots) of a design for a CI. A new PCA must be held for each line, and each time a line is restarted. The length of down time prior to such a re-start is usually... read more
Physical Decomposition
A decomposition in the “physical” domain, where the pieces are tangible. To be valid, it must be shown using the laws of physics (e.g., conservation of mass, conservation of energy, continuity of potential difference) that the sum of the parts is exactly equivalent to the whole of the parent. Contrast with Functional Decomposition.
Physically Allocated Baseline
A type of baseline in which the architecture is defined by the manufactured product structure. In the legacy, a collection of C-specifications subordinate to a single parent CI.
Plan C
The first, best plan (Plan A) is always to do things right, and this is where you should always start. The next best plan (Plan B) is to come as close to right as you can given the real world constraints under which you labor (inclusive of schedule, budget, technology, manufacturing capability, and nincompoops). The... read more
Pointer
In the context of Computer Science, a “pointer” is a way to store the “memory address” at which real information is stored. Among other uses, programmers employ it when the memory resources are not all allocated when the executable is loaded. In many programming languages, pointers sort of inherit the data type of the data... read more
Politics
Activities concerned with achieving control, advancement, or some other goal within (or between) groups of people by way of persuasion, intimidation, compromise or outright supersession. Political methods are the antitheses of Engineering methods, but they’re sometimes necessary in order to get anything done at all.
Portable (Software)
In software development, Application software that can be compiled to run unchanged on any of several different operating systems. If an application is not portable, the source code must be changed in order to be compiled for a different operating system than it was originally written for. There are degrees of portability depending on the... read more
Precedence
The order in which various similar factors are considered. Most frequently used in the Engineering context when referring to which documents over-rule which other documents.
Precision
The granularity (fineness) with which a number is quoted, sometimes described to as “the repeatability limits”. Contrast with accuracy, tolerance, and uncertainty.
Preliminary Design
The collection(s) of design features, which may or may not constitute a comprehensive design, corresponding to the development specifications authenticated at PDR and used to establish the feasibility of the Functionally Allocated Baseline established at the end of that program phase.
Preliminary Design Review (PDR)
The review (contrast with “audit”) at which it is determined that a feasible allocation of development requirements can be made to an identified set of Configuration Items, such that a Functional Baseline can be implemented with reasonable cost and schedule. The review may occur over an extended period of time, culminating with authentication of the development specifications.... read more
Preloaded Joints
A “preloaded” joint is one where the bolt(s) have been tensioned beyond what it takes to just barely make the two sides touch. When a preloaded joint is subsequently subjected to an external “separating” load, part of that load goes into trying to pull those sides apart, and part of it goes into the bolt... read more
Pricing Instructions
A set of field-leveling rules supplied to respondents in an RFQ or RFP. The PI can be an important, and complicated, part of a solicitation. It can include (but is not limited to) directions for handling different types and instances of TBD, for use of inflation data, or for handling of uncertainties. It usually requires... read more
Primary Structure
In the general aerospace industry, primary structural loads are generally those affecting flight, pressurization, or ground handling capability1. In the case of the Common Berthing Mechanism, a product-specific definition applied2: “That part of a flight vehicle or element which sustains the significant applied loads and provides main load paths for distributing reactions of applied loads.... read more
Prime Contract
A contract let by the Acquisition Customer for an entire project. This type of contract is, therefore, distinct from all sub-contracts let by the Prime Contractor or any sub-contractor thereof. All money for the project tracks back to one or more Prime Contracts. It is possible for a single sub-contract to trace to more than... read more
Prime Item
Anecdotally, a CEI on a Prime Contract and, therefore, the subject of a Type B1 specification in accordance with MIL-STD-490. Lower-order CI’s could also be CEI’s (especially late in the contract, as maintenance items were formally identified), but these (the Prime Items) were considered the heavy-hitters.
Procedure
A defined sequence of circumstances, actions, reactions, status, feedback and expected outcomes which, when implemented by or on behalf of one or more operators, achieve some technical objective. Contrast with process and algorithm, which are more typically reserved for the context of software.
Process
In the vernacular, a repeatable activity or repeatable set of interrelated activities that collectively create a set of one or more outputs from a set of one or more inputs. A set (which may, or may not, include parallelization) of steps (tasks or logical instructions) not necessarily having a defined, internally managed set of terminating criteria.... read more
Procurement Control Drawing (PCD)
A class of drawing, some sub-types of which are identifying, that is used to purchase outside Engineered materiel or Engineering services. PCD types include Envelope Drawings, Source Control Drawings, and Vendor Item Control Drawings. The sub-types evolve in very different ways depending on who pays for different types of associated Intellectual Property.
Product
The stuff that actually gets turned over to an Acquisition Customer in exchange for cold, hard cash. Contrast with Service (meaning 2).
Product Line
A group1 of related Products. The relationship may be one of design derivation or evolution, similarity in technology, collocation of fabrication facilities, or any other factor causing a particular organization to designate them for collective management. Footnotes Which might be temporally sequential[↩]
Product Requirement
A requirement for the as-built condition of each S/N of a design which, when met, constitutes one element of justification for marking the item with a Part Number. Sometimes referred to as “Fabrication Requirement”. Contrast with Development Requirement. In legacy practice, Product Requirements were collected into Product/Fabrication Specifications.
Product Structure
The hierarchical organization of Part Numbers comprising one or more individual products, which may (or may not) be related.
Product/Fabrication Specification
A type of specification associated with a specific Part Number or group of Part Numbers; sometimes referred to as a “C-spec”. The requirements address whether an acceptable “instance” of a design has, in fact, been produced. In many cases, this type of specification was little more than a reference to a CEI’s identifying drawing (or,... read more
Production
The act of actually fabricating a deliverable product wherein Engineering gets dragged into the realities of things like cost effectiveness and productivity after the pie-in-the-sky design phase, but before the living hell that is Test 1. Footnotes Don’t get me wrong. I like the test phase, and have always got along well with people who spend... read more
Production Drawing
A Manufacturing Drawing used for rate production (as opposed to, for example, a one-off).
Program
A collection of one or more contracts being managed at a single site, typically sharing a common customer, technology, and/or product line, and usually under the supervision of a single individual (a “Program Manager”).
Program Change Proposal (PCP)
A proposed major change to a program’s SoW or T&C simultaneously impacting multiple clauses of both, including (but not limited to) changes in schedule and DIL. Contrast with the technical focus of an ECP.
Program End Item (PEI)
In certain legacy practices, a CI where both the customer and supplier are within the same organization (therefore, no formal contractual relationship exists, and the lawyers can’t get involved). Contrast with CEI.
Program Executive Office (PEO)
In DoD Acquistion practice, the office with procurement authority over a broadly defined class of system, generally covering more than a single Program. Superior to a PMO.
Program Management Office (PMO)
In DoD Acquisition practice, the office with procurement authority over a single Program. Subordinate to a PEO.
Prospective Deduction
In many cases of deduction, the premeses have prior, independent acceptance of validity. System Engineering (SE) practices accept unvalidated1 assertions as premeses, provided that they are subsequently subjected to formal validation as part of the development process. In the context of requirement derivation, dealing with validation of the premeses is an important part of traceability to... read more
Proximate Cause
A proximate cause is an event or circumstance immediately adjacent to a result. Contrast with root cause, causal factor, and distal cause.
Qualification (Qual)
The process of showing that a design meets the requirements formally allocated to a CI. Contrast with Acceptance, and bear in mind that whereas we qualify the design, we accept the part.
Qualification Requirement
A technical requirement used as a criterion to determine whether development of a CI is competently complete (and that the developer should therefore be paid). In theory, synonymous with “development requirement” except that things don’t always end the way they started. The best way to use this term is in the past tense: “the Qualification... read more
Qualitative Requirement
In a perfect world, all characteristics could be parameterized. Unfortunately, the world is less than perfect: some requirements remain “qualitative” and, therefore, unmeasured. That situation is often problematic, because it is difficult to determine whether or not such requirements have been met. In many cases, non-quantification can be addressed through the use of a surrogate verification... read more
Quality Assurance (QA)
The supervisory process of independently acknowledging the validity of conformance by an S/N or L/N to the allocated requirements as they were asserted by some non-disinterested party. Generally effected by line inspectors of as-built items or as-run formal test, inspection (2), or demonstration.
Quality Engineering (QE)
A branch of Engineering chartered with ensuring that the proper inspection (and related data) are present and correct in the manufacturing drawings and formal test procedures.