This glossary contains terms and acronyms used within the &os; community and documentation. ACL ACPI AMD AML API APIC APM APOP ASL ATA ATM ACPI Machine Language AML Pseudocode, interpreted by a virtual machine within an ACPI-compliant operating system, providing a layer between the underlying hardware and the documented interface presented to the OS. ACPI Source Language ASL The programming language AML is written in. Access Control List ACL Advanced Configuration and Power Interface ACPI A specification which provides an abstraction of the interface the hardware presents to the operating system, so that the operating system should need to know nothing about the underlying hardware to make the most of it. ACPI evolves and supercedes the functionality provided previously by APM, PNPBIOS and other technologies, and provides facilities for controlling power consumption, machine suspension, device enabling and disabling, etc. Application Programming Interface API A set of procedures, protocols and tools that specify the canonical interaction of one or more program parts; how, when and why they do work together, and what data they share or operate on. Advanced Power Management APM Advanced Programmable Interrupt Controller APIC Advanced Technology Attachment ATA Asynchronous Transfer Mode ATM Authenticated Post Office Protocol APOP Automatic Mount Daemon AMD A daemon that automatically mounts a filesystem when a file or directory within that filesystem is accessed. BIND BIOS BSD Basic Input/Output System BIOS The definition of BIOS depends a bit on the context. Some people refer to it as the ROM chip with a basic set of routines to provide an interface between software and hardware. Others refer to it as the set of routines contained in the chip that help in bootstrapping the system. Some might also refer to it as the screen used to configure the boostrapping process. The BIOS is PC-specific but other systems have something similar. Berkeley Internet Name Domain BIND An implementation of the DNS protocols. Berkeley Software Distribution BSD 這是由 U.C. Berkeley 的 Computer Systems Research Group(CSRG) 選來當作他們所改良、修改過的 AT&T's 32V &unix; 名稱。&os; 則是由 CSRG 的這個心血衍生出來。 Bikeshed Building A phenomenon whereby many people will give an opinion on an uncomplicated topic, whilst a complex topic receives little or no discussion. See the FAQ for the origin of the term. CD CHAP CLIP COFF CPU CTS CVS Carrier Detect CD An RS232C signal indicating that a carrier has been detected. Central Processing Unit CPU Also known as the processor. This is the brain of the computer where all calculations take place. There are a number of different architectures with different instruction sets. Among the more well-known are the Intel-x86 and derivatives, Sun SPARC, PowerPC, and Alpha. Challenge Handshake Authentication Protocol CHAP Classical IP over ATM CLIP Clear To Send CTS An RS232C signal giving the remote system permission to send data. Common Object File Format COFF Concurrent Versions System CVS DAC DDB DES DHCP DNS DSDT DSR DTR DVMRP Discretionary Access Control DAC Data Encryption Standard DES Data Set Ready DSR Data Terminal Ready DTR Debugger DDB Differentiated System Description Table DSDT Distance-Vector Multicast Routing Protocol DVMRP Domain Name System DNS The system that converts humanly readable hostnames (i.e., mail.example.net) to Internet addresses and vice versa. Dynamic Host Configuration Protocol DHCP A protocol that dynamically assigns IP addresses to a computer (host) when it requests one from the server. The address assignment is called a lease. ECOFF ELF ESP Encapsulated Security Payload ESP Executable and Linking Format ELF Extended COFF ECOFF FADT FAT FAT16 FTP File Allocation Table FAT File Allocation Table (16-bit) FAT16 File Transfer Protocol FTP A member of the family of high-level protocols implemented on top of TCP which can be used to transfer files over a TCP/IP network. Fixed ACPI Description Table FADT GUI Giant The name of a mutual exclusion mechanism (a sleep mutex) that protects a large set of kernel resources. Although a simple locking mechanism was adequate in the days where a machine might have only a few dozen processes, one networking card, and certainly only one processor, in current times it is an unacceptable performance bottleneck. &os; developers are actively working to replace it with locks that protect individual resources, which will allow a much greater degree of parallelism for both single-processor and multi-processor machines. Graphical User Interface GUI A system where the user and computer interact with graphics. HTML HUP HangUp HUP HyperText Markup Language HTML The markup language used to create web pages. I/O IASL IMAP IP IPFW IPP IPv4 IPv6 ISP IP Firewall IPFW IP Version 4 IPv4 The IP protocol version 4, which uses 32 bits for addressing. This version is still the most widely used, but it is slowly being replaced with IPv6. IP Version 6 IPv6 The new IP protocol. Invented because the address space in IPv4 is running out. Uses 128 bits for addressing. Input/Output I/O Intel’s ASL compiler IASL Intel’s compiler for converting ASL into AML. Internet Message Access Protocol IMAP Internet Printing Protocol IPP Internet Protocol IP The packet transmitting protocol that is the basic protocol on the Internet. Originally developed at the U.S. Department of Defense and an extremly important part of the TCP/IP stack. Without the Internet Protocol, the Internet would not have become what it is today. For more information, see RFC 791. Internet Service Provider ISP A company that provides access to the Internet. KAME Japanese for turtle, the term KAME is used in computing circles to refer to the KAME Project, who work on an implementation of IPv6. KDC KLD KSE KVA Kbps Kernel &man.ld.1; KLD Kernel Scheduler Entities KSE A kernel-supported threading system. See the project home page for further details. Kernel Virtual Address KVA Key Distribution Center KDC Kilo Bits Per Second Kbps Used to measure bandwith (how much data can pass a given point at a specified amount of time). Alternates to the Kilo prefix include Mega, Giga, Tera, and so forth. LAN LOR LPD Line Printer Daemon LPD Local Area Network LAN A network used on a local area, e.g. office, home, or so forth. Lock Order Reversal LOR The &os; kernel uses a number of resource locks to arbitrate contention for those resources. A run-time lock diagnostic system found in &os.current; kernels (but removed for releases), called &man.witness.4;, detects the potential for deadlocks due to locking errors. (&man.witness.4; is actually slightly conservative, so it is possible to get false positives.) A true positive report indicates that if you were unlucky, a deadlock would have happened here. True positive LORs tend to get fixed quickly, so check &a.current.url; and the LORs Seen page before posting to the mailing lists. MAC MADT MFC MFP4 MFS MIT MLS MOTD MTA MUA Mail Transfer Agent MTA An application used to transfer email. An MTA has traditionally been part of the BSD base system. Today Sendmail is included in the base system, but there are many other MTAs, such as postfix, qmail and Exim. Mail User Agent MUA An application used by users to display and write email. Mandatory Access Control MAC Massachusetts Institute of Technology MIT Merge From Current MFC MFC 是一個縮寫，它代表了 Merged From -CURRENT ，這字眼會在 CVS logs 中常見， 以表示這是從 -CURRENT 中整合進其他分支(通常是 -STABLE)的 patch 或功能。 Merge From Perforce MFP4 To merge functionality or a patch from the Perforce repository to the -CURRENT branch. Merge From Stable MFS In the normal course of FreeBSD development, a change will be committed to the -CURRENT branch for testing before being merged to -STABLE. On rare occasions, a change will go into -STABLE first and then be merged to -CURRENT. This term is also used when a patch is merged from -STABLE to a security branch. Message Of The Day MOTD A message, usually shown on login, often used to distribute information to users of the system. Multi-Level Security MLS Multiple APIC Description Table MADT NAT NDISulator NFS NTFS NTP Network Address Translation NAT Network File System NFS New Technology File System NTFS A filesystem developed by Microsoft and available in its New Technology operating systems, such as &windows2k;, &windowsnt; and &windowsxp;. Network Time Protocol NTP OBE ODMR OS On-Demand Mail Relay ODMR Operating System OS A set of programs, libraries and tools that provide access to the hardware resources of a computer. Operating systems range today from simplistic designs that support only one program running at a time, accessing only one device to fully multi-user, multi-tasking and multi-process systems that can serve thousands of users simultaneously, each of them running dozens of different applications. Overtaken By Events OBE Indicates a suggested change (such as a Problem Report or a feature request) which is no longer relevant or applicable due to such things as later changes to &os;, changes in networking standards, the affected hardware having since become obsolete, and so forth. p4 PAE PAM PAP PC PCNSFD PDF PID POLA POP POP3 PPD PPP PPPoA PPPoE PPP over ATM PPPoA PPP over Ethernet PPPoE PR PXE Password Authentication Protocol PAP Perforce A source code control product made by Perforce Software which is more advanced than CVS. Although not open source, it use is free of charge to open-source projects such as &os;. Some &os; developers use a Perforce repository as a staging area for code that is considered too experimental for the -CURRENT branch. Personal Computer PC Personal Computer Network File System Daemon PCNFSD Physical Address Extensions PAE A method of enabling access to up to 64 GB of RAM on systems which only physically have a 32-bit wide address space (and would therefore be limited to 4 GB without PAE). Pluggable Authentication Modules PAM Point-to-Point Protocol PPP Pointy Hat A mythical piece of headgear, much like a dunce cap, awarded to any &os; committer who breaks the build, makes revision numbers go backwards, or creates any other kind of havoc in the source base. Any committer worth his or her salt will soon accumulate a large collection. The usage is (almost always?) humorous. Portable Document Format PDF Post Office Protocol POP Post Office Protocol Version 3 POP3 PostScript Printer Description PPD Preboot eXecution Environment PXE Principle Of Least Astonishment POLA 在 &os; 的發展過程中，任何的改變幅度，都不該讓使用者習慣感到不適。 舉例來說：若任意調動 /etc/defaults/rc.conf 中的系統啟動順序， 就是違背 POLA 原則的精神。任何開發人員，都該在做出重大改變前， 先三思是否會與 POLA 原則有所違背。 Problem Report PR A description of some kind of problem that has been found in either the &os; source or documentation. See Writing &os; Problem Reports. Process ID PID A number, unique to a particular process on a system, which identifies it and allows actions to be taken against it. Project Evil The working title for the NDISulator, written by Bill Paul, who named it referring to how awful it is (from a philosophical standpoint) to need to have something like this in the first place. The NDISulator is a special compatibility module to allow Microsoft Windows™ NDIS miniport network drivers to be used with &os;/i386. This is usually the only way to use cards where the driver is closed-source. See src/sys/compat/ndis/subr_ndis.c. RA RAID RAM RD RFC RISC RPC RS232C RTS Random Access Memory RAM Received Data RD Recommended Standard 232C RS232C A standard for communications between serial devices. Reduced Instruction Set Computer RISC Redundant Array of Inexpensive Disks RAID Remote Procedure Call RPC repocopy Repository Copy repocopy(repository copy 的縮寫) 就是直接從 CVS repository 中複製檔案。 若不用 repocopy 的方式，那麼若要在 repository 內複製、移動檔案的話， committer 就必須執行 cvs add 來把檔案放到新位置， 並且還要執行 cvs rm 來刪除舊檔。 剛剛講的這種方式的缺點在於，該檔的之前相關紀錄 (比如在 CVS logs 中的相關項目)並不會隨之而複製到新地方去。 而 &os; 計劃中認為這些歷史記錄都是相當有用的， 所以會經常採用 repository copy 的方式。 這也就是為何 repository 管理員會直接在 repository 內複製檔案的方式， 而非採取 &man.cvs.1; 程式來進行 cvs add、 cvs rm之類的動作。 Request For Comments RFC A set of documents defining Internet standards, protocols, and so forth. See www.rfc-editor.org. Also used as a general term when someone has a suggested change and wants feedback. Request To Send RTS Router Advertisement RA SCI SCSI SG SMB SMP SMTP SMTP AUTH SSH STR SMTP Authentication SMTP AUTH Server Message Block SMB Signal Ground SG An RS232 pin or wire that is the ground reference for the signal. Simple Mail Transfer Protocol SMTP Secure Shell SSH Small Computer System Interface SCSI Suspend To RAM STR Symmetric MultiProcessor SMP System Control Interrupt SCI TCP TCP/IP TD TFTP TGT TSC Ticket-Granting Ticket TGT Time Stamp Counter TSC A profiling counter internal to modern &pentium; processors that counts core frequency clock ticks. Transmission Control Protocol TCP A protocol that sits on top of (e.g.) the IP protocol and guarantees that packets are delivered in a reliable, ordered, fashion. Transmission Control Protocol/Internet Protocol TCP/IP The term for the combination of the TCP protocol running over the IP protocol. Much of the Internet runs over TCP/IP. Transmitted Data TD Trivial FTP TFTP UDP UFS1 UFS2 UID URL USB Uniform Resource Locator URL Unix File System Version 1 UFS1 Unix File System Version 2 UFS2 Universal Serial Bus USB User ID UID A unique number assigned to each user of a computer, by which the resources and permissions assigned to that user can be identified. User Datagram Protocol UDP VPN Virtual Private Network VPN