Textual Criticism, Literary Criticism and How to Read Apparatus Criticus (with Abbreviations and Terms Explained)

Manuscripts, Textual Criticism and Literary Criticism

Let me start with a bitter truth: none of the ancient texts we possess today is the original manuscript written by the author’s own hand.

Imagine it’s the year 54 BC. The literary circles of Rome are filled with talk of the poems of a certain Lucretius. As an aristocrat with a taste for literature, we’re eager to read his work. But how?

If we personally know the poet, we might ask one of our skilled slaves to copy the original manuscript for us. If not, we could borrow a friend’s copy—someone who’s already done this—and have our own made. Failing that, we could simply stop by a bookseller and purchase a ready-made copy. These copies would continue to be reproduced and passed from hand to hand for years, even centuries. Each new copy would be made from a previous one, which itself had been copied from yet another.

The vast majority of ancient texts we have today survive in manuscripts dating to the 9th century AD. This means there is often a chain of transmission stretching over a thousand years between the original version written by the author and the version we now possess.

Scribes could make mistakes out of simple carelessness: writing dolores (“pains”) instead of labores (“toils”) for instance. They might accidentally repeat a word, or omit one that appeared twice deliberately in the source. Worse still, scribes—or even readers—might take pen in hand to remove lines or words they didn’t like, or insert expressions they found pleasing. So, to what extent can a text that has undergone such a long and uncertain process of transmission still resemble what the author originally wrote?

One of the most important sub-disciplines of Classical Studies, textual criticism (or as some prefer to call it, higher philology) aims to identify such errors and present the work in its most authentic possible form. If the text contains a phrase that the author never actually wrote, then all of our interpretations, conclusions, and elaborate theories based on that passage may be rendered invalid. This is why textual criticism forms one of the foundational pillars upon which Classical Studies has risen.

Copying errors in ancient texts have been known for thousands of years; in fact, even in Antiquity, we find efforts to recover the original form of texts. For example, as we learn from Aulus Gellius¹ who lived in the 2nd century AD, the following line appears in Vergil’s Georgics:²

“and with its bitter flavour will distort the testers’ soured mouths.
et ora tristia temptantum sensu torquebit amaro

In all known copies of the Georgics during Gellius’ time, the line appeared in this form. However, his friend Iulius Hyginus claimed to have seen and read the original manuscript of the Georgics at Vergil’s house, and reported that the line was actually written as follows:

“But the bitterness of the sensation will distort the testers’ soured mouths.”
et ora tristia temptantum sensus torquebit amaror

The first version appears more natural, and the educated people of the time also found the version Hyginus called “original” to be odd.³ However, another friend of Gellius pointed out that the same usage occurs in the poetry of Lucretius, a poet whom Vergil greatly respected. In other words, Vergil had deliberately written it that way, imitating a poet he admired. But the scribes thought this expression was a mistake and “corrected” Vergil’s lines!

As the example above illustrates, the life of an ancient text filled with interventions begins the moment it leaves the author’s hands. Minor spelling errors, such as writing surpa instead of supra, have been noticed and corrected for millennia. For instance, in the works of just three authors—Catullus, Propertius, and the first six books of Tacitus’ Annales—there are nearly a thousand such corrections that are widely accepted without dispute.

However, it is far more difficult to determine which reading among various manuscripts truly reflects the author’s original when the difference is not a simple spelling mistake and does not obviously disrupt the flow of the text. In one manuscript, a verb may appear in the present tense (producit), while in another it is in the future tense (producet); one might contain an affirmative form, while another includes a negation (non producit); one may use the possessive pronoun tuus (“your”), while another uses meus (“my”); or one version might read “by the power of religion” (religionis vim), while another reads “by the power of the legion” (legionis vim). Complex issues like these demand much more careful and systematic approaches.

We mentioned earlier that textual criticism has been practiced since very early times. However, it was not until the 19th century that this discipline acquired a systematic and scientific methodology. A young philologist named Karl Lachmann brought together all the surviving manuscripts of Lucretius’ work and, by analyzing their similarities and differences, reconstructed a kind of “family tree.” In other words, he created a stemma, a diagram showing which manuscripts were likely copied from which others.

To better understand what this method involves, let’s take a look at a particularly simple stemma proposed by Konrad Müller, who studied the manuscript tradition of Lucretius.

Figure 1: The Stemma of the Italian manuscripts of Lucretius posited by Konrad Müller (1973)

Figure 1 presents the stemma created by Konrad Müller in 1973, showing the manuscript tradition of the Italian copies of Lucretius’ De Rerum Natura. Such diagrams aim to model which manuscripts may have descended from others by analyzing patterns of similarity and variation among them.

At the top of the diagram, the Greek letter π (pi) represents a hypothetical lost manuscript that is believed to be the common ancestor of all extant copies. Symbols like ξ (xi) and φ (phi) beneath it indicate intermediate sources from which groups of similar manuscripts are thought to have descended.

The manuscripts labeled with capital Latin letters represent physical copies that have survived to the present day. When these manuscripts share the same textual features, it is usually assumed that they were copied from a common source. For example, if the manuscripts A, B, L, and P contain the same word or phrase that is missing in F and C, it is likely that A, B, L, and P descend from a shared intermediary, represented by the symbol ξ in the diagram.

These kinds of stemmatic diagrams help us determine which manuscripts may be more reliable, which are likely to contain more errors, and which group of texts belongs to which textual tradition. In doing so, the editor can work toward reconstructing the earliest and most accurate version of the text not by relying on a single manuscript, but by examining the entire tradition in a systematic way.

The first to apply this genealogy-based approach in a systematic manner was Karl Lachmann, whose pioneering work earned great praise. He was even called “the Prometheus of textual criticism.” The method he employed quickly became one of the foundational principles of modern textual criticism and is now named after him: the Lachmann method. It is also known as the stemmatic method, genealogical analysis, or the common error method.

The process of comparing the manuscripts and identifying copying errors (recensio) is relatively straightforward compared to the much more controversial stage that follows: the correction of those errors—known as emendatio or coniectura. Simple scribal mistakes are usually corrected without objection. However, not all corrections are so clear-cut. Some proposed readings or emendations are highly debated, and there may be no scholarly consensus on which version is most accurate.

For example, nearly all manuscripts of Ovid’s Amores 2.4.11–12 transmit the following lines:

“If a woman has lowered her chaste eyes toward me,
I burn; that very modesty becomes a snare for me.”

sive aliqua est oculos in me deiecta modestos
uror et insidiae sunt pudor ille meae

However, this reading presents some semantic oddities. First, the verb deicere (“to lower”) seems somewhat out of place. Moreover, from the Roman point of view, it is unusual for a chaste woman to “lower her eyes to” a man who is not her husband. To resolve this difficulty, some scholars have proposed emending in me (“to me”) to in se (“to herself”). While this revision may resolve the issue of modesty, it creates a new problem: “a woman lowering her eyes to herself” feels semantically weak and artificial.

At this point, some editors have proposed a more radical solution: replacing in me/se with humum (“to the ground”). This would render the line as:

“If a woman modestly lowers her eyes to the ground,
I burn with desire; her modesty itself becomes a trap for me.”

Moreover, this usage appears elsewhere in Ovid’s Amores.⁴ With this emendation, the lines become flawless in both meaning and elegance.

However, the problem is clear: instead of choosing me, the reading found in most manuscripts, or opting for se by assuming a scribal slip, some editors propose an entirely different word—humum—which has no manuscript support whatsoever. In the absence of solid evidence, accepting such an emendation is entirely up to the reader. As Tarrant puts it, “Textual criticism operates not with proof or certainty, but with probabilities and persuasion.” Roger Dawe notes that between 1890 and 1960, editors proposed some 20,000 emendations to the texts of Aeschylus. How many of those might actually be correct? Dawe’s estimate is about 0.1%—in other words, just 20.

With the previous example, we’ve begun to drift from textual criticism into the waters of literary criticism. Literary criticism, in its simplest form, involves analyzing the content of a text. It is another way to determine whether something within it might be corrupt. As one might expect, this approach is far more subjective and therefore much more controversial than textual criticism. Let’s now turn to an example that perfectly illustrates it.

In lines 6.817–18 of Vergil’s Aeneid, we read:

“Would you also see the Tarquin kings, the arrogant spirit of
Brutus the Avenger, and the fasces regained?

vis et Tarquinios reges animamque superbam
ultoris Bruti fascesque videre receptos?

These lines have been the subject of debate since Late Antiquity, beginning with commentators like Servius and Donatus. The controversy arises from the phrase animam superbam (“the arrogant soul”), which refers to Brutus, the founder of the Republic, even though the epithet superbus (“arrogant”) is associated with King Tarquinius.

There is no manuscript variation here. However, readers have been puzzled by Vergil’s description of L. Iunius Brutus as superbus (“arrogant”). Since Brutus is considered a hero of the Roman Republic, it has been argued that Vergil would not have criticized him in this way. To resolve this “inconsistency,” scholars have proposed various emendations over the centuries. For instance, Peerlkamp suggested altering the lines as follows:

“Brutus, the avenger of the arrogant soul (i.e., King Tarquinius)”

animaeque superbae ultorem Brutum

On the other hand, some scholars argue that there is no need to question these lines. Given that Brutus had his two young sons executed, they suggest that perhaps Vergil was deliberately drawing attention to another side of his character. This debate is highly instructive, as it reveals not only how meaning can be contested, but also how the ideological expectations of the reader or editor can shape the interpretation of a text.

Another type of textual corruption can, ironically, arise from the scribes’ own attempts to “correct” the text as we saw in the Gellius case. For example a medieval scribe might “fix” a sentence he believed to be erroneous. Even worse, another scribe might omit a line he disliked altogether, or insert a verse of his own between. This is known as interpolatio. In his Teubner edition of Ovid’s Metamorphoses, Rudolph Merkel suggested that as many as 250 lines had been added to the text later. In contrast, Ehwald, in his next Teubner edition of the same work, considered only one of these lines to be questionable.

Scribes’ interventions are not limited to adding or removing material from the text. Some scribes, acting like proto-editors, compared and combined two different manuscripts, thus creating a hybrid text (contaminatio), or attempted to “correct” the meaning by altering the order of lines (transpositio). Of course, interventions to the text are not limited to scribes alone. For instance, the owner of a 13th-century manuscript, living in the 15th century, might have thought a word in the text was incorrect, crossed it out, and written what he believed to be the correct form in the margin.

What is Critical Edition and How to Read Apparatus Criticus

Literary works are immensely valuable sources for understanding classical civilizations. However, as we have seen above, the versions of these texts that have come down to us often contain various interventions and copying errors, which can occasionally cast doubt on their reliability. Yet a significant portion of our knowledge about the ancient world relies precisely on these texts. For this reason, reconstructing them as closely as possible to the author’s original form is of great importance.

Thanks to the intensive scholarly focus on this field in the 19th century onwards, Classical Studies gradually acquired a more scientific character. The most concrete outcome of this effort is the critical edition. A critical edition is created by systematically comparing and evaluating all known manuscripts of a text. In these editions, the main text established by the editor is given at the top of the page; At the bottom, there is a notes section called the apparatus criticus or critical apparatus. The apparatus systematically presents the variant readings found in different manuscripts, proposed emendations, scribal errors, and the editor’s choices. This allows the reader to see not only the text itself but also the sources, decisions, and debates on which that text is based. As a result, philological, historical, and literary interpretations rest on a much firmer foundation.

There are several publishing houses that produce critical editions at a professional level, though with minor methodological differences. The most well-known among them are Teubner (Bibliotheca Scriptorum Graecorum et Romanorum Teubneriana) and the Oxford Classical Texts (OCT) series. While critical editions generally follow established conventions, variations may occur depending on the editor’s approach and the specific characteristics of the text.

Now let’s take a look at a critical edition through an example. The edition I’ll be using is Oratio Cum Senatui Gratias Agit by Cicero, edited by Maslowski and published in 1981 by Teubner.

Praefatio and Sigla Page

The praefatio (preface), typically found at the beginning of critical editions, is usually written in Latin. However, in recent years, some editions have included introductions in English as well. In the praefatio, the editor presents the manuscripts used, explains their editorial approach and guiding principles, notes any special conventions they follow, and briefly discusses previous scholarship on given text. While editors generally adhere to established conventions, different editorial approaches may be adopted depending on the nature of the text. Such choices are explained in the praefatio.

Following the praefatio, critical editions usually include a list of manuscripts. On this page, the various manuscripts that serve as sources for the text are enumerated, each assigned a identifying letter known as a siglum. In our example, the manuscripts are labeled as P, G, E, H etc. A siglum often relates to the city or library where the manuscript is housed. For instance, P represents a 9th-century codex from Paris, catalogued as number 7794.

While our example does not include such a case, it is common for multiple manuscripts to come from the same location—say, the Vatican Library. In such instances, different letters may be assigned, or numbering may be used, such as V1 and V2. Some editors distinguish older manuscripts with uppercase Latin letters and newer ones with lowercase letters.

We have previously seen (Figure 1) that lowercase Greek letters can be used for hypothetical manuscripts. However, they may also be employed to group manuscripts that are closely related or fall before or after a certain historical threshold. These are called collective sigla. In our example, all manuscripts except X and F are grouped under the symbol ω, while a few later manuscripts are grouped under ς.

Sometimes, the same manuscript contains writing or corrections made by more than one hand. In these cases, numbers are added to the siglum to distinguish them. The handwriting of the original scribe is referred to as prima manus (the first hand) and is marked with a superscript, as in P¹. A second hand would be noted as P², a third as P³, and so on. The approximate date of each hand can often be identified by features like script style or ink color. For instance, Gothic script usually points to the 13th century, while Humanist script suggests the 15th century. In our example, the second hand dates to roughly the same period as the original scribe, whereas the third hand is considerably later.

Under the Notae section, we find abbreviations of the surnames of various scholars—most of whom are themselves editors.

Text Page and Apparatus Criticus

Figure 4: Text page.

A typical page in a critical edition usually consists of four main parts. Figure 4 above shows page 164 of the Oxford Classical Texts edition of Noctes Atticae by Aulus Gellius, edited by P. K. Marshall and published in 1968. I chose this page instead of the Cicero edition we examined earlier because of its simpler layout.

From top to bottom, the page can be divided into the following sections:

Main text: This section at the top contains the Latin text as established by the editor. The editorial signs and choices seen in the text will be discussed below in the apparatus section.

Line numbers: There are two sets of line numbers, one on the left and one on the right. The column on the left (marked as 1 in Figure 4) shows the continuous line numbering of the entire work. In the top left corner, “IV.i” indicates the book and chapter. Using this system, the line marked “14” on the left, which begins Scire, inquit ridens iam…, can be cited as Gell. NA IV.1.14. This lets other researchers quickly locate the exact passage in Aulus Gellius’s Noctes Atticae book 4, section 1, line 14. For standard abbreviations of ancient texts, see: https://oxfordre.com/classics/page/3993

The column on the right (2) shows the line numbers for this specific page. These are mainly used to help locate notes in the apparatus. Not every line is numbered; usually only every fifth line is marked. However, we can still identify, for example, that the third line is the second line above the one marked “5”.

Classical footnotes: These notes appear just below the main text (3) and are not related to textual criticism. Instead, they offer references or brief explanations, often literary or historical. For example, the note under line 15 reads Aen. I. 703, indicating that Gellius’s phrase quid Vergilius refers to line 703 of Book 1 in Vergil’s Aeneid.

Apparatus criticus: This section (4) is separated by a horizontal line at the bottom of the page. At first glance, it may seem complex or even incomprehensible, but it is actually highly systematic. The apparatus provides short notes recording variant readings, manuscript differences, and editorial decisions. Once you understand its basic structure, reading the apparatus becomes much more manageable than it first appears.

Latin is particularly suited to this kind of technical notation, as it conveys a great deal of meaning with very few words. For this reason, unlike the praefatio, I have never seen an apparatus written in English. Given the long-established tradition of using Latin, it is unlikely that this will change any time soon.

Now, let’s examine a few entries from the apparatus.

3 dicere VPR: discere A
In line 3, the word dicere appears in manuscripts V, P, and R, whereas manuscript A reads discere. The editor has chosen to follow the VPR manuscript tradition and adopted dicere in the main text.

4 tum V: tu P :om. R
In line 4, the phrase tum profecto mihi is written as tum in manuscript V and tu in P. The abbreviation om. stands for omisit (omitted); thus, neither of these words is found in manuscript R.

22 posculentum VR: postulentum P¹: potulentum P²
In line 22, the word posculentum is found in manuscripts V and R. However, manuscript P contains two different readings written by two different hands. P¹ (the original scribe, or prima manus) wrote postulentum, while a later hand (P²) corrected it to potulentum.

24 add. Hertz.
In line 24, we see the expression <aut familiae> enclosed in angle brackets. These brackets indicate words not found in any manuscript but added by the editor. The entry add. Hertz. tells us that this addition (addidit) was first proposed by Hertz (1883–1885). Marshall, the editor of the edition we are using, has adopted this suggestion in the main text while indicating in the apparatus that the conjecture was not his own but Hertz. As a general rule, a conjecture is attributed to the scholar who first proposed it. Meanwhile, the names of the editors are sometimes Latinized, e.g., Bentley becomes Bentleius.

eos VPR: eum Carrio.
Again in line 24, the manuscripts V, P, and R read eos. However, in his 1585 edition, L. Carrio argued that the correct reading should be eum. Marshall did not accept this suggestion and retained the traditional eos in the text but he still found it worthwhile to inform the reader and therefore included it in the apparatus.

2 lac. stat. Mommsen.
Among all the pages, it seems I’ve managed to find one with a printing error. The line number “2” in this entry should actually be “25.” The abbreviation lac. stat. stands for lacuna statuit, meaning “a gap has been identified.” The scholar who identified it is the renowned historian and philologist Theodor Mommsen. If we look at line 25 of the text, we find a series of three asterisks (***), indicating the location of presumed missing passage.

We have seen the three main components typically encountered in an apparatus criticus: variant readings among manuscripts, scribal interventions, and editorial additions or corrections. However, keep in mind that I intentionally chose a relatively simple apparatus. You will certainly encounter more complex ones. Still, I hope this has helped convey the basic logic of how an apparatus works. You can refer to the list of abbreviations at the end of this article to decode the more complex entries.

Abbreviations and Terms

In the apparatus criticus, editors may occasionally provide extended explanations for specific cases; however, turning this section into a commentarium is generally discouraged. To keep the apparatus as concise as possible, lots of abbreviations are employed. Yet a few abbreviations and signs can vary between editions, particularly between older and newer ones.

While alphabetical order is essential for abbreviation lists in printed editions, digital formats free us from this constraint thanks to the Ctrl+F function. This flexibility has allowed me to group abbreviations under thematic headings based on their meaning and usage. As a result, abbreviations with similar meanings or that often appear together are listed consecutively, making the list more functional for users. Some abbreviations could belong to multiple categories, but they are listed under the one where they are most frequently found.

Double consonants (e.g., ms for manuscript, mss for manuscripts) indicate the plural. In Latin, the letters u and v represent the same sound. I have used v throughout, but in other editions, you may see u used instead.

Signs Found in the Text

[], {} letters or words omitted by the editor
< > letters or words added by the editor
† † (obelus) indicates a word or passage believed to be corrupt
/// erasure
*** (asteriscus) a gap or lacuna in the manuscript

General Abbreviations and Terms

(These are not direct interventions in the text, but rather guiding or descriptive terms.)

ed., edd. = editor, editores
ed. pr. = editio princeps: first printed edition
v., vv. = versus (verse(s) or line number(s) e.g., Aen. I.703)
h.v. = hunc versum: this verse
v., vd. = vide: see
cf. = confer: compare
al. = alii / alibi: others / elsewhere
ad = at, on
ap. = apud: at
e, ex = from / based on
pro = instead of
inf. = infra / inferior: below / later
sup. = supra: above
ante = before
prius, prior = earlier
alterum = next, following
ca. = circa: about, approximately
fere = nearly, generally
nonnulli = some (usually as nonnulli editores: some editors)
vel = or
pler. = plerique: most, the majority
plur., pll = plures: many
sim. = similia: similar
vel sim. = vel simile: or similar
numeri = numbers, metrical structure
loc. = locus / locum: place in a text
ll., litt. = litterae: letters
s.v. = sub voce: under the word or heading (in dictionary or index entry)
signum interrogandi / interrogationis = question mark

Manuscript, Readings and Location

(Physical/philological terms related to manuscripts, variant readings, and paleographic interventions.)

autograph: the author’s lost original script
exemplar: the manuscript used as a source for copying
archetype: the hypothetical earliest ancestor of extant copies
hyparchetype: a hypothetical intermediate ancestor from which a subgroup of manuscripts derives
apograph: a copy made from a specific manuscript
traditio: tradition; the transmission of the text through manuscripts
MS, MSS = manuscript(s)
siglum, sigla: the identifying symbol(s) assigned to manuscripts (P, V, G, ω, φ, etc.)
cod., codd., cet., cett. = codex, codices, ceterus, ceteri: manuscript(s), the other(s) (as the remaining manuscripts)
vett. = veteres: older manuscripts
recc. = recentiores: later manuscripts
dett. = deteriores: inferior-quality manuscripts (a pejorative term often used for late copies)
ς = symbol typically used for late manuscripts
rell. = reliqui: the remaining manuscripts
ω = symbol typically used for all manuscripts
m. = manus: hand (the scribe’s handwriting)
m.p. = manus prima: the first hand (the primary scribe’s handwriting; may also be indicated with a siglum and superscript 1, e.g., V¹. If two different scribes wrote parts of the same manuscript, subscript numbers may be used, e.g., V₁ V₂)
m.r. = manus recentior: a later hand (a different scribe than the primary; indicated with superscript 2, 3, etc., e.g., V², V³)

lect. = lectio: reading (of the word or phrase in a manuscript)
variant reading: different readings found for the same passage across different manuscripts
error: a mistake made during copying
corruptio: corruption (unclear, incorrect, or incomplete passage)
interpolatio: a later addition inserted into the text
add. = addidit: added
corr. = correxit: corrected
om. = omisit: omitted
def. = deficit: lacking (sometimes as defendit: defended)
deest, desunt = is missing / are missing
inscr. = inscriptum / inscriptio: written / a title or later addition
i.t. = in textu: in the text
non leg. = non legitur / leguntur: illegible
fr. = fragmentum: fragmentary
lac. = lacuna: a gap in the text

l. = linea: line
s.l., ss., sscr., suprascr. = supra lineam / supra scriptum: above the line / above the script
subscr. = subscriptum: below the line
interl. = inter lineas: between the lines
mg, marg. = margin
i.m. = in margine: in the margin
ras. = rasura: erasure
in ras., i.r. = in rasura: over an erasure
p.r. = post rasuram: after the erasure
a.r. = ante rasuram: before the erasure
lit. = litura: ink smudge

Editorial Intervention and Comment

(Editorial conjectures and comments regarding textual corrections, variant readings, or interventions)

coniectura / emendatio: A conjectural correction suggested by an editor not found in any manuscript. (In cases where a textual problem is identified but no convincing solution is found, the term diagnostic conjecture may be used.)
coni., conj., ci = coniecit: proposed (made a conjectural correction)
scripsi = I wrote (i.e. this is my own)
correctio: the correction of an incorrect reading
cor. = correxit: corrected
em., emend. = emendavit: corrected
suppletio: a proposal to fill in a missing portion of the text
suppl. = supplevit: supplied (added to the text)
deletio: the removal of a portion of the text
del. = delevit: deleted
exp. = expunxit: erased
secl. = seclusit: bracketed (considered not part of the text)
eiecit = expelled (removed from the text)
damnatio: the judgment that a passage is a later interpolation
damn. = damnavit: condemned (determined to be interpolated)
abiud. = abiudicavit: ruled against (judged as an interpolation)
ins. = inseruit: inserted
transp., transt., trai. = transposuit / transtulit / traiecit: transposed (e.g. moved line 6 before line 9)
cont. = continuavit: considered the passage to be continuous (e.g. Socrates continues speaking until line 4, with no change of speaker)
interpunxit = added punctuation (leviter = lightly: comma, etc.; graviter = heavily: period, colon, etc.)
dist. = distinxit: separated (inserted punctuation)
stat. = statuit: determined (often used with lacuna)
indic. = indicavit: indicated (often with lacuna)
addub. = addubitavit: doubted
susp. = suspicatus est: suspected
prob. = probavit: approved (of a reading or conjecture)
cens. = censuit: deemed appropriate
temptavit = attempted
malim = I would prefer
possis = possibly preferable
sc., scil. = scilicet: certainly
recte = rightly, correctly
vid., ut vid. = ut videtur: as it seems
fort., fors. = fortasse / forsan: perhaps
an, anne = maybe?
inc., incert. = incertum (uncertain)
n. l. = non liquet: it is unclear
dub. = dubitanter / dubius: doubtful
pot. qu. = potius quam: rather than
praeeunte = under the guidance of (usually used with an editor’s name)
iam = already (referring to a previously proposed reading)
alii alia (coniecerunt) = others differently (proposed: refers to other unnamed conjectures)

INVESTIGABILIS

Textual Criticism, Literary Criticism and How to Read Apparatus Criticus (with Abbreviations and Terms Explained)

Manuscripts, Textual Criticism and Literary Criticism